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/package.json

@@ -19,7 +19,6 @@
     "fastify": "^5.2.0",
     "js-chess-engine": "^2.4.6",
     "pino": "^9.5.0",
-    "ws": "^8.18.0",
     "zod": "^3.24.0"
   },
   "devDependencies": {
@@ -28,6 +27,7 @@
     "pino-pretty": "^11.3.0",
     "tsx": "^4.19.2",
     "typescript": "^5.6.0",
-    "vitest": "^3.0.0"
+    "vitest": "^3.0.0",
+    "ws": "^8.18.0"
   }
 }