Refactor large files into modular components

- Refactored page.tsx (613→252 lines) with GameOverScreen and LeftPanel extracted
- Refactored StatsTab.tsx (584→92 lines) with section components
- Refactored SkillsTab.tsx (434→54 lines) with sub-components
- Created modular structure for GameContext, LootInventory, and other components
- All extracted components organized into feature directories

src/lib/game/stores/index.ts

@@ -17,7 +17,8 @@ export type { SkillState } from './skillStore';
 export { useCombatStore, makeInitialSpells } from './combatStore';
 export type { CombatState } from './combatStore';
 
-export { useGameStore, useGameLoop } from './gameStore';
+export { useGameStore } from './gameStore';
+export { useGameLoop } from './gameHooks';
 export type { GameCoordinatorState, GameCoordinatorStore } from './gameStore';
 
 // Re-export utilities from utils.ts