feat(modifiers): bundle preset activations on profiles + editor Presets tab

Profiles can now carry a list of PresetActivation entries alongside
their per-type / per-instance modifiers. When such a profile is
picked in the Lobby, its bundled presets are unioned with any
layout suggestedPresets (profile config wins on id-collision).

Changes:

- ModifierProfile.presetActivations added (optional readonly array).
  Zod schema + server wire schema mirror the field; drift guard
  picks up forgotten updates on either side.
- ModifierProfileEditor grows a Presets tab in the right column
  sharing space with the Library tab. Each preset row carries a
  checkbox, scope radio (both/white/black), and a turns counter
  (blank = permanent). Inline diagnostics warn on redundant layout
  overlap and on loose-scope incompatibility; hard errors under
  overlapping scope disable Save.
- Lobby merges profile.presetActivations into its active preset
  set on profile select, on editor close, and on URL deep-link.
- LayoutPicker suggested-preset chips now expose aria-pressed so
  the active state is readable by assistive tech + e2e tests.

Tests: library round-trip preserves presetActivations (unit); two
new e2e scenarios (pre-seeded bundled profile auto-activates; full
editor-author loop persists + reflects in the lobby). 1752 unit +
105 playwright all green.

packages/server/src/protocol.ts

@@ -260,6 +260,19 @@ export type InstanceModifierWire = z.infer<typeof InstanceModifierSchema>;
  * drift without requiring us to export the chess-side zod schema across
  * a zod major-version boundary.
  */
+/**
+ * Wire schema for a bundled preset activation. Shape-mirrored with
+ * chess-side `PresetActivation` in presets/active-set.ts. We don't
+ * enum-check `id` against the registry here — the engine tolerates
+ * unknown ids and the drift guard below only checks key parity with
+ * the chess-side type.
+ */
+export const PresetActivationWireSchema = z.object({
+  id: z.string().min(1),
+  scope: z.enum(["both", "white", "black"]),
+  turnsRemaining: z.number().int().positive().nullable(),
+});
+
 export const ModifierProfileSchema = z.object({
   id: z.string().min(1),
   name: z.string().min(1),
@@ -267,6 +280,7 @@ export const ModifierProfileSchema = z.object({
   layoutId: z.string().optional(),
   perType: z.array(TypeModifierSchema),
   perInstance: z.array(InstanceModifierSchema),
+  presetActivations: z.array(PresetActivationWireSchema).optional(),
   version: z.literal(1),
   source: z.enum(["premade", "custom"]),
 });