feat(phase1.1): create hook module structure with proper exports

- Create new hook modules: useBoard, useCursor, useGameStatus
- Move/copy hook implementations to their own directories
- Create index.ts files for clean module exports
- Update all imports to use new module locations
- Rename useSnake -> useCursor for Unified API alignment
- Rename useRenderer -> useBoard for clarity
- Update main src/index.ts to export from all hook modules
- All TypeScript builds successfully
- Example app remains functional

src/index.ts

@@ -1,3 +1,7 @@
 export * from './useGame';
+export * from './useCursor';
+export * from './useGameStatus';
+export * from './useBoard';
+export * from './useScore';
 export * from './types';