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/StudyProgress.tsx

@@ -4,7 +4,7 @@ import { Button } from '@/components/ui/button';
 import { Progress } from '@/components/ui/progress';
 import { BookOpen, X } from 'lucide-react';
 import { SKILLS_DEF, SPELLS_DEF } from '@/lib/game/constants';
-import { formatStudyTime } from '@/lib/game/formatting';
+import { formatStudyTime } from '@/lib/game/utils/formatting';
 import type { StudyTarget } from '@/lib/game/types';
 
 interface StudyProgressProps {