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>

realtime/consumers.py

@@ -0,0 +1,61 @@
+import json
+from urllib.parse import parse_qs
+
+from channels.generic.websocket import AsyncJsonWebsocketConsumer
+
+from fupogfakta.models import Player
+
+
+class GameConsumer(AsyncJsonWebsocketConsumer):
+    """
+    WebSocket consumer for a game session.
+
+    URL: ws/game/<session_code>/
+
+    Query params:
+      - session_token: player session token (players only)
+      - role=host: skip token check for host in MVP
+    """
+
+    async def connect(self):
+        self.session_code = self.scope["url_route"]["kwargs"]["session_code"].upper()
+        self.group_name = f"game_{self.session_code}"
+
+        query_string = self.scope.get("query_string", b"").decode()
+        params = parse_qs(query_string)
+
+        role = params.get("role", [None])[0]
+        session_token = params.get("session_token", [None])[0]
+
+        if role != "host":
+            if not session_token:
+                await self.close(code=4001)
+                return
+
+            try:
+                self.player = await Player.objects.aget(
+                    session_token=session_token,
+                    session__code=self.session_code,
+                )
+            except Player.DoesNotExist:
+                await self.close(code=4003)
+                return
+        else:
+            self.player = None
+
+        await self.channel_layer.group_add(self.group_name, self.channel_name)
+        await self.accept()
+
+    async def disconnect(self, close_code):
+        if hasattr(self, "group_name"):
+            await self.channel_layer.group_discard(self.group_name, self.channel_name)
+
+    async def receive_json(self, content, **kwargs):
+        if content.get("type") == "ping":
+            await self.send_json({"type": "pong"})
+
+    # --- Group message handlers ---
+
+    async def phase_event(self, event):
+        """Forward any phase_event broadcast to the WebSocket client."""
+        await self.send_json(event["payload"])