docs: design doc for fup og fakta game engine + platform architecture

Captures all brainstormed decisions:
- Pluggable game cartridge platform (GameDriver interface)
- Celery + Redis timer-driven phase transitions
- Session owner play/pause/exit controls (no skip)
- Escalating scoring per round, incremental reveal scoring
- Emoji reactions during guess phase → post-game awards
- Relational per-user config presets with game-specific models
- Ephemeral game state (no persistence after exit/finish)
- Full WebSocket event reference and data lifecycle

Also: updated TODO.md (WebSocket done, persisted answers done),
created CLAUDE.md, and PROMPT.md for ralph-loop.

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

partyhub/asgi.py

@@ -1,11 +1,15 @@
 import os
-from channels.routing import ProtocolTypeRouter
+
+from channels.routing import ProtocolTypeRouter, URLRouter
 from django.core.asgi import get_asgi_application
 
 os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'partyhub.settings')
 
 django_asgi_app = get_asgi_application()
 
+from realtime.routing import websocket_urlpatterns  # noqa: E402 — must come after env setup
+
 application = ProtocolTypeRouter({
     'http': django_asgi_app,
+    'websocket': URLRouter(websocket_urlpatterns),
 })