chore(modifiers): remove unused BUILTIN_MODIFIER_KIND_IDS export

T3 audit gap 6. Added during the T29 schema widening as a documentation
anchor; zero consumers found in the audit. The authoritative list of
built-in ids lives in MODIFIER_REGISTRY (consumed by PerTypePanel's
dropdown and the engine's apply pipeline); duplicating it here is
churn without benefit. Dropping the export narrows the package's
public surface and eliminates a drift risk.

packages/chess/src/modifiers/schema.ts

@@ -17,23 +17,6 @@ import type { ModifierProfile } from "./types.js";
 // Primitives
 // ---------------------------------------------------------------------------
 
-/**
- * Built-in modifier ids — preserved as a literal enum for documentation
- * and editor-side completion. Not used as the parse schema directly
- * because T3 widens `kind` to also accept user-authored CustomModifierIds
- * (arbitrary strings); the runtime apply path (T22) dispatches via
- * MODIFIER_REGISTRY first then engine.customModifiers, silently skipping
- * unknown kinds.
- */
-export const BUILTIN_MODIFIER_KIND_IDS = [
-  "hp-bonus",
-  "range-bonus",
-  "direction-additions",
-  "capture-flags",
-  "promotion-override",
-  "damage-resistance",
-] as const;
-
 /**
  * Parse-time schema for `kind`: any non-empty string. T3 custom modifier
  * ids are arbitrary strings (e.g. "custom:my-shield"), so an enum check
@@ -42,7 +25,9 @@ export const BUILTIN_MODIFIER_KIND_IDS = [
  *
  * Validity of the kind is enforced ELSEWHERE: the apply pipeline looks
  * the id up in MODIFIER_REGISTRY (built-ins) then engine.customModifiers
- * (user-authored). Unknown kinds are warned and skipped.
+ * (user-authored). Unknown kinds are warned and skipped. The
+ * authoritative list of built-in ids lives in MODIFIER_REGISTRY, not
+ * duplicated here.
  */
 const ModifierKindIdSchema = z.string().min(1);