refactor: trim over-engineering (ponytail-audit)

- ws → devDependencies (src uses type-only; runtime comes via @fastify/websocket)
- delete bot/index.ts barrel; import casual-brain/driver directly
- untrack tsconfig.tsbuildinfo (already gitignored)
- vanillaCandidates: push-loop → .map()

94 tests pass, build clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/server/src/bot/candidates.ts

@@ -27,11 +27,7 @@ function vanillaCandidates(game: Game, color: Color): CandidateMove[] {
   const moves = game.chess.moves({ verbose: true }) as Array<{
     from: Square; to: Square; promotion?: PromotionType;
   }>;
-  const out: CandidateMove[] = [];
-  for (const m of moves) {
-    out.push({ from: m.from, to: m.to, promotion: m.promotion });
-  }
-  return out;
+  return moves.map((m) => ({ from: m.from, to: m.to, promotion: m.promotion }));
 }
 
 function blindCandidates(game: Game, color: Color): CandidateMove[] {