refactor: remove GUARDIANS constant, consolidate into guardian-data.ts

- Delete src/lib/game/constants/guardians.ts (the old static GUARDIANS constant)
- Create src/lib/game/data/guardian-data.ts with BASE_GUARDIANS (same data, new home)
- Remove GUARDIANS export from constants/index.ts
- Update all 11 files that imported GUARDIANS to use getGuardianForFloor() or BASE_GUARDIANS:
  - useGameDerived.ts, combat-actions.ts, gameStore.ts, prestigeStore.ts
  - combat-utils.ts, room-utils.ts, floor-utils.ts, spire-utils.ts
  - SpireCombatPage.tsx, SpireHeader.tsx
- Update 4 test files to use getGuardianForFloor() instead of GUARDIANS constant
- guardian-encounters.ts now imports BASE_GUARDIANS from guardian-data.ts
- Split room-utils.test.ts (505 lines) into room-utils.test.ts + room-utils-floor-state.test.ts

src/lib/game/stores/prestigeStore.ts

@@ -5,7 +5,8 @@ import { create } from 'zustand';
 import { persist } from 'zustand/middleware';
 import { createSafeStorage } from '../utils/safe-persist';
 import type { Memory } from '../types';
-import { GUARDIANS, PRESTIGE_DEF } from '../constants';
+import { PRESTIGE_DEF } from '../constants';
+import { getGuardianForFloor } from '../data/guardian-encounters';
 import { ok, okVoid, fail, ErrorCode } from '../utils/result';
 import type { Result } from '../utils/result';
 
@@ -151,7 +152,7 @@ export const usePrestigeStore = create<PrestigeStore>()(
 
       startPactRitual: (floor: number, rawMana: number) => {
         const state = get();
-        const guardian = GUARDIANS[floor];
+        const guardian = getGuardianForFloor(floor);
         if (!guardian) return fail(ErrorCode.INVALID_INPUT, `No guardian at floor ${floor}`);
 
         if (!state.defeatedGuardians.includes(floor)) return fail(ErrorCode.GUARDIAN_NOT_DEFEATED, `Guardian at floor ${floor} has not been defeated`);
@@ -178,7 +179,7 @@ export const usePrestigeStore = create<PrestigeStore>()(
         const state = get();
         if (state.pactRitualFloor === null) return;
 
-        const guardian = GUARDIANS[state.pactRitualFloor];
+        const guardian = getGuardianForFloor(state.pactRitualFloor);
         if (!guardian) return;
 
         set({