cleanup: delete computed-stats.ts shim and store/index.ts

- Delete src/lib/game/computed-stats.ts (root-level re-export shim)
- Delete src/lib/game/store/index.ts (nothing imports from it)
- Update __tests__/computed-stats.test.ts to import from ../utils instead
- Clean up craftingStore.ts imports (remove unused useGameStore, CraftingApply)

Typecheck and lint pass (pre-existing DisciplinesTab.tsx errors unchanged)

src/components/game/TimeDisplay.tsx

@@ -1,7 +1,7 @@
 'use client';
 
 import { fmt } from '@/lib/game/stores';
-import { formatHour } from '@/lib/game/formatting';
+import { formatHour } from '@/lib/game/utils/formatting';
 
 interface TimeDisplayProps {
   day: number;