Initial project scaffold

Full-stack homeschool web app with FastAPI backend, Vue 3 frontend,
MySQL database, and Docker Compose orchestration. Includes JWT auth,
WebSocket real-time TV dashboard, schedule builder, activity logging,
and multi-child support.

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

backend/app/websocket/manager.py

@@ -0,0 +1,42 @@
+import json
+import logging
+from collections import defaultdict
+
+from fastapi import WebSocket
+
+logger = logging.getLogger(__name__)
+
+
+class ConnectionManager:
+    def __init__(self):
+        # child_id → list of active WebSocket connections
+        self.active: dict[int, list[WebSocket]] = defaultdict(list)
+
+    async def connect(self, websocket: WebSocket, child_id: int) -> None:
+        await websocket.accept()
+        self.active[child_id].append(websocket)
+        logger.info("WS connected for child %d — %d total", child_id, len(self.active[child_id]))
+
+    def disconnect(self, websocket: WebSocket, child_id: int) -> None:
+        self.active[child_id].discard(websocket) if hasattr(self.active[child_id], "discard") else None
+        try:
+            self.active[child_id].remove(websocket)
+        except ValueError:
+            pass
+        logger.info("WS disconnected for child %d — %d remaining", child_id, len(self.active[child_id]))
+
+    async def broadcast(self, child_id: int, message: dict) -> None:
+        """Send a JSON message to all TVs watching a given child."""
+        dead = []
+        for ws in list(self.active.get(child_id, [])):
+            try:
+                await ws.send_text(json.dumps(message))
+            except Exception:
+                dead.append(ws)
+
+        for ws in dead:
+            self.disconnect(ws, child_id)
+
+
+# Singleton — imported by routers and the WS endpoint
+manager = ConnectionManager()