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/combat-actions.ts

@@ -2,7 +2,8 @@
 // Pure combat logic — no cross-store getState() calls.
 // All external data (signedPacts, etc.) is passed in as parameters.
 
-import { SPELLS_DEF, GUARDIANS, HOURS_PER_TICK } from '../constants';
+import { SPELLS_DEF, HOURS_PER_TICK } from '../constants';
+import { getGuardianForFloor } from '../data/guardian-encounters';
 import type { CombatStore, CombatState } from './combat-state.types';
 import type { SpellState } from '../types';
 import { getFloorMaxHP, getFloorElement, calcDamage, canAffordSpellCost, deductSpellCost } from '../utils';
@@ -114,16 +115,16 @@ export function processCombatTick(
 
       // Check if floor is cleared
       if (floorHP <= 0) {
-        const wasGuardian = GUARDIANS[currentFloor];
-        onFloorCleared(currentFloor, !!wasGuardian);
+        const guardian = getGuardianForFloor(currentFloor);
+        onFloorCleared(currentFloor, !!guardian);
 
         currentFloor = Math.min(currentFloor + 1, 100);
         floorMaxHP = getFloorMaxHP(currentFloor);
         floorHP = floorMaxHP;
         castProgress = 0;
 
-        if (wasGuardian) {
-          logMessages.push(`⚔️ ${wasGuardian.name} defeated!`);
+        if (guardian) {
+          logMessages.push(`\u2694\ufe0f ${guardian.name} defeated!`);
         } else if (currentFloor % 5 === 0) {
           logMessages.push(`🏰 Floor ${currentFloor - 1} cleared!`);
         }