feat: v3 — fight loop, expanded challenges, FightPage ownership guard

- Add fight-loop CLI for automated mock fights with elo-based matchmaking
- Expand challenge types, scoring narrations, arenas, and mock bot pool
- FightPage "Fight again" buttons now only show for your own bot
- FightViewer async scene init, live fight polling with round counter
- Extract mock answers into separate answers module

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/package.json

@@ -7,6 +7,7 @@
     "build": "tsc",
     "start": "node dist/index.js",
     "seed": "tsx src/seed.ts",
+    "fight-loop": "tsx src/fight-loop-cli.ts",
     "migrate": "tsx src/db/migrate.ts"
   },
   "dependencies": {