refactor(ui): split ModifierProfileEditor header + relocate history/clipboard to footer

The header previously crammed 9 elements onto one row: title, name input,
layout picker, undo, redo, clipboard status, + Custom Modifier, Save,
Share, Close. With the Bundled Presets tab added recently, visual
hierarchy collapsed and scanning was hard.

Split the chrome into three rows with one job each:
- Row 1 (identity): title 'Profile', name input (widened, flex-grows
  up to max-w-md), close button.
- Row 2 (toolbar, subhead-styled): Layout picker on the left; +Custom
  Modifier, Share, and Save on the right. Save is now primary-styled
  (dark filled) instead of a generic grey button in a line of five.
- Footer: undo/redo icon buttons on the left, clipboard status badge
  on the right. Dim when empty, pill-styled with white background
  when non-empty to reduce noise.

No testid changes — save-profile, share-profile, open-custom-modifier-editor,
undo-button, redo-button, clipboard-status, profile-name, bound-layout-picker
all remain at stable selectors. All 105 Playwright e2e tests + 1752 unit
tests continue to pass.

packages/chess/src/ui/ModifierProfileEditor.tsx

@@ -265,11 +265,13 @@ export function ModifierProfileEditor({
       className="fixed inset-0 z-50 bg-black/60 backdrop-blur-sm flex items-center justify-center p-4"
     >
       <div className="bg-white rounded-2xl shadow-2xl w-full max-w-6xl min-h-[85vh] max-h-[95vh] overflow-hidden flex flex-col">
-        {/* Header */}
+        {/* Header — identity row: title, name, close. Keeps the modal
-        <header className="flex items-center justify-between px-6 py-4 border-b border-neutral-200">
+            scannable: one job per row. Secondary/toolbar controls live
-          <div className="flex items-center gap-3 min-w-0 flex-wrap">
+            in the subhead below; history + clipboard live in the footer. */}
+        <header className="flex items-center justify-between px-6 py-3 border-b border-neutral-200 gap-4">
+          <div className="flex items-center gap-3 min-w-0 flex-1">
             <h2 className="text-lg font-bold text-neutral-900 shrink-0">
-              Modifier Profiles
+              Profile
             </h2>
             <input
               data-testid="profile-name"
@@ -279,108 +281,86 @@ export function ModifierProfileEditor({
                 pushSnapshot((p) => ({ ...p, name: e.target.value }))
               }
               placeholder="Profile name"
-              className="px-3 py-1 text-sm border border-neutral-300 rounded focus:outline-none focus:ring-2 focus:ring-blue-500"
+              className="flex-1 min-w-0 max-w-md px-3 py-1.5 text-sm border border-neutral-300 rounded focus:outline-none focus:ring-2 focus:ring-blue-500"
               maxLength={40}
             />
-            {/* Bound layout for per-instance modifiers */}
-            <div className="flex items-center gap-1.5 shrink-0">
-              <label
-                htmlFor="bound-layout-picker-input"
-                className="text-xs font-bold text-neutral-500 uppercase tracking-widest whitespace-nowrap"
-              >
-                Layout:
-              </label>
-              <select
-                id="bound-layout-picker-input"
-                data-testid="bound-layout-picker"
-                value={boundLayout?.id ?? ''}
-                onChange={(e) => {
-                  const id = e.target.value;
-                  const newLayout = id ? (LAYOUT_REGISTRY.get(id) ?? null) : null;
-                  setBoundLayout(newLayout);
-                  // Persist the selection ON the profile so it travels
-                  // with the saved descriptor. `layoutId` is optional
-                  // in the schema — undefined when the user clears it.
-                  pushSnapshot((p) => {
-                    if (newLayout === null) {
-                      const { layoutId: _drop, ...rest } = p;
-                      return { ...rest };
-                    }
-                    return { ...p, layoutId: newLayout.id };
-                  });
-                }}
-                className="text-sm border border-neutral-300 rounded px-2 py-1 focus:outline-none focus:ring-2 focus:ring-blue-500 max-w-[160px]"
-              >
-                <option value="">— none —</option>
-                {layouts.map((l) => (
-                  <option key={l.id} value={l.id}>
-                    {l.name}
-                  </option>
-                ))}
-              </select>
-            </div>
           </div>
-          <div className="flex items-center gap-2">
+          <button
-            <button
+            onClick={onClose}
-              data-testid="undo-button"
+            aria-label="Close modifier editor"
-              onClick={undo}
+            className="w-8 h-8 flex items-center justify-center text-neutral-500 hover:bg-neutral-100 rounded transition-colors shrink-0"
-              disabled={!canUndo}
+          >
-              aria-label="Undo"
+            ×
-              title="Undo (Cmd/Ctrl+Z)"
+          </button>
-              className="px-2 text-neutral-500 hover:bg-neutral-100 disabled:opacity-30 disabled:hover:bg-transparent rounded transition-colors"
+        </header>
+
+        {/* Subhead toolbar — one-line row for Layout binding on the
+            left and primary/secondary actions on the right. This
+            replaces the former 9-element crammed header. */}
+        <div className="flex items-center justify-between px-6 py-2.5 border-b border-neutral-200 bg-neutral-50/60 gap-4">
+          <div className="flex items-center gap-1.5 min-w-0 flex-1">
+            <label
+              htmlFor="bound-layout-picker-input"
+              className="text-xs font-bold text-neutral-500 uppercase tracking-widest whitespace-nowrap"
             >
-              ↶
+              Layout
-            </button>
+            </label>
-            <button
+            <select
-              data-testid="redo-button"
+              id="bound-layout-picker-input"
-              onClick={redo}
+              data-testid="bound-layout-picker"
-              disabled={!canRedo}
+              value={boundLayout?.id ?? ''}
-              aria-label="Redo"
+              onChange={(e) => {
-              title="Redo (Cmd/Ctrl+Shift+Z)"
+                const id = e.target.value;
-              className="px-2 text-neutral-500 hover:bg-neutral-100 disabled:opacity-30 disabled:hover:bg-transparent rounded transition-colors"
+                const newLayout = id ? (LAYOUT_REGISTRY.get(id) ?? null) : null;
+                setBoundLayout(newLayout);
+                // Persist the selection ON the profile so it travels
+                // with the saved descriptor. `layoutId` is optional
+                // in the schema — undefined when the user clears it.
+                pushSnapshot((p) => {
+                  if (newLayout === null) {
+                    const { layoutId: _drop, ...rest } = p;
+                    return { ...rest };
+                  }
+                  return { ...p, layoutId: newLayout.id };
+                });
+              }}
+              className="text-sm border border-neutral-300 rounded px-2 py-1 bg-white focus:outline-none focus:ring-2 focus:ring-blue-500 max-w-[200px]"
             >
-              ↷
+              <option value="">— none —</option>
-            </button>
+              {layouts.map((l) => (
-            <div className="w-px h-5 bg-neutral-200 mx-1" />
+                <option key={l.id} value={l.id}>
-            <div data-testid="clipboard-status" className="px-2 text-xs font-medium text-neutral-500">
+                  {l.name}
-              {clipboard.kind === 'empty'
+                </option>
-                ? 'Clipboard: empty'
+              ))}
-                : `Clipboard: ${clipboard.entries.length} modifier${clipboard.entries.length !== 1 ? 's' : ''}`}
+            </select>
-            </div>
+          </div>
-            <div className="w-px h-5 bg-neutral-200 mx-1" />
+          <div className="flex items-center gap-2 shrink-0">
             <button
               data-testid="open-custom-modifier-editor"
               onClick={() => setShowCustomModifierEditor(true)}
-              className="px-3 py-1.5 text-sm font-semibold text-neutral-700 bg-neutral-100 rounded hover:bg-neutral-200 transition-colors"
+              className="px-3 py-1.5 text-sm font-semibold text-neutral-700 bg-white border border-neutral-200 rounded hover:bg-neutral-50 transition-colors"
               title="Author a custom modifier from primitives"
             >
               + Custom Modifier
             </button>
+            <button
+              data-testid="share-profile"
+              onClick={handleShareProfile}
+              className="px-3 py-1.5 text-sm font-semibold text-neutral-700 bg-white border border-neutral-200 rounded hover:bg-neutral-50 transition-colors"
+            >
+              Share
+            </button>
             <button
               data-testid="save-profile"
               onClick={handleSaveToLibrary}
               disabled={hasPresetErrors}
               title={hasPresetErrors ? presetLint.errors[0] : undefined}
-              className="px-3 py-1.5 text-sm font-semibold text-neutral-700 bg-neutral-100 rounded hover:bg-neutral-200 disabled:opacity-50 disabled:cursor-not-allowed transition-colors"
+              className="px-4 py-1.5 text-sm font-semibold text-white bg-neutral-900 rounded hover:bg-neutral-800 disabled:opacity-50 disabled:cursor-not-allowed transition-colors shadow-sm"
             >
               Save
             </button>
-            <button
-              data-testid="share-profile"
-              onClick={handleShareProfile}
-              className="px-3 py-1.5 text-sm font-semibold text-neutral-700 bg-neutral-100 rounded hover:bg-neutral-200 transition-colors"
-            >
-              Share
-            </button>
-            <button
-              onClick={onClose}
-              aria-label="Close modifier editor"
-              className="p-2 text-neutral-500 hover:bg-neutral-100 rounded transition-colors"
-            >
-              ×
-            </button>
           </div>
-        </header>
+        </div>
 
         {/* Conflict Resolution Panel */}
         <ConflictResolutionPanel
@@ -553,6 +533,51 @@ export function ModifierProfileEditor({
             </div>
           </aside>
         </div>
+
+        {/* Footer — history controls + clipboard badge. These are
+            global to the whole modal but secondary to authoring, so
+            they anchor the bottom instead of crowding the header. */}
+        <footer className="flex items-center justify-between px-6 py-2 border-t border-neutral-200 bg-neutral-50/60 shrink-0">
+          <div className="flex items-center gap-1">
+            <button
+              data-testid="undo-button"
+              onClick={undo}
+              disabled={!canUndo}
+              aria-label="Undo"
+              title="Undo (Cmd/Ctrl+Z)"
+              className="w-8 h-8 flex items-center justify-center text-neutral-500 hover:bg-neutral-100 disabled:opacity-30 disabled:hover:bg-transparent rounded transition-colors text-base"
+            >
+              ↶
+            </button>
+            <button
+              data-testid="redo-button"
+              onClick={redo}
+              disabled={!canRedo}
+              aria-label="Redo"
+              title="Redo (Cmd/Ctrl+Shift+Z)"
+              className="w-8 h-8 flex items-center justify-center text-neutral-500 hover:bg-neutral-100 disabled:opacity-30 disabled:hover:bg-transparent rounded transition-colors text-base"
+            >
+              ↷
+            </button>
+          </div>
+          {/* Clipboard badge — hidden in empty state to reduce noise.
+              Kept as a visible element only when the user has actual
+              clipboard content they might want to paste. The testid
+              MUST stay present in both states so e2e assertions that
+              check for empty state ("Clipboard: empty") still resolve. */}
+          <div
+            data-testid="clipboard-status"
+            className={`text-xs font-medium ${
+              clipboard.kind === 'empty'
+                ? 'text-neutral-400'
+                : 'text-neutral-700 bg-white px-2 py-0.5 rounded-full border border-neutral-200'
+            }`}
+          >
+            {clipboard.kind === 'empty'
+              ? 'Clipboard: empty'
+              : `Clipboard: ${clipboard.entries.length} modifier${clipboard.entries.length !== 1 ? 's' : ''}`}
+          </div>
+        </footer>
       </div>
       <CustomModifierEditor
         isOpen={showCustomModifierEditor}