Add Phase 2: integrations, admin, and remaining commands

New commands: agent, trivia (with 30s timer reveal), ask (Ollama LLM
with cooldown), minecraft (RCON whitelist), health (admin-only metrics).
Adds metrics tracking, per-user cooldowns, and admin permission checks.

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

requirements.txt

@@ -2,3 +2,4 @@ matrix-nio[e2e]
 python-dotenv
 aiohttp
 markdown
+mcrcon