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/components/game/tabs/GuardianPactsTab.test.ts

@@ -29,8 +29,9 @@ describe('Tab barrel export', () => {
 
 describe('Guardian data', () => {
   it('all guardians have required fields', async () => {
-    const { GUARDIANS } = await import('@/lib/game/constants/guardians');
-    for (const [floor, def] of Object.entries(GUARDIANS)) {
+    const { getGuardianForFloor } = await import('@/lib/game/data/guardian-encounters');
+    for (const floor of [10, 20, 30, 40, 50, 60, 80, 90, 100]) {
+      const def = getGuardianForFloor(floor)!;
       expect(def.name).toBeTruthy();
       expect(def.element).toBeTruthy();
       expect(def.hp).toBeGreaterThan(0);
@@ -49,10 +50,10 @@ describe('Guardian data', () => {
   });
 
   it('guardians are defined at expected floors', async () => {
-    const { GUARDIANS } = await import('@/lib/game/constants/guardians');
+    const { getGuardianForFloor } = await import('@/lib/game/data/guardian-encounters');
     const expectedFloors = [10, 20, 30, 40, 50, 60, 80, 90, 100];
     for (const floor of expectedFloors) {
-      expect(GUARDIANS[floor]).toBeDefined();
+      expect(getGuardianForFloor(floor)).not.toBeNull();
     }
   });
 
@@ -62,8 +63,9 @@ describe('Guardian data', () => {
       'critChance', 'critDamage', 'spellEfficiency', 'manaGain', 'insightGain',
       'studySpeed', 'prestigeInsight',
     ];
-    const { GUARDIANS } = await import('@/lib/game/constants/guardians');
-    for (const def of Object.values(GUARDIANS)) {
+    const { getGuardianForFloor } = await import('@/lib/game/data/guardian-encounters');
+    for (const floor of [10, 20, 30, 40, 50, 60, 80, 90, 100]) {
+      const def = getGuardianForFloor(floor)!;
       for (const boon of def.boons) {
         expect(validBoonTypes).toContain(boon.type);
         expect(boon.value).toBeGreaterThan(0);