Add user ping system and room deletion functionality

Backend changes:
- Fix track deletion foreign key constraint (tracks.py)
  * Clear current_track_id from rooms before deleting track
  * Prevent deletion errors when track is currently playing

- Implement user ping/keepalive system (sync.py, websocket.py, ping_task.py, main.py)
  * Track last pong timestamp for each user
  * Background task sends ping every 30s, disconnects users after 60s timeout
  * Auto-pause playback when room becomes empty
  * Remove disconnected users from room_participants

- Enhance room deletion (rooms.py)
  * Broadcast room_deleted event to all connected users
  * Close all WebSocket connections before deletion
  * Cascade delete participants, queue, and messages

Frontend changes:
- Add ping/pong WebSocket handling (activeRoom.js)
  * Auto-respond to server pings
  * Handle room_deleted event with redirect to home

- Add room deletion UI (RoomView.vue, HomeView.vue, RoomCard.vue)
  * Delete button visible only to room owner
  * Confirmation dialog with warning
  * Delete button on room cards (shows on hover)
  * Redirect to home page after deletion

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/app/services/sync.py

@@ -2,24 +2,39 @@ from typing import Dict, Set
 from fastapi import WebSocket
 from uuid import UUID
 import json
+import time
+import asyncio
 
 
 class ConnectionManager:
     def __init__(self):
         # room_id -> set of (websocket, user_id)
         self.active_connections: Dict[UUID, Set[tuple[WebSocket, UUID]]] = {}
+        # (room_id, user_id) -> last pong timestamp
+        self.last_pong: Dict[tuple[UUID, UUID], float] = {}
+        # Ping interval and timeout in seconds
+        self.ping_interval = 30  # Отправлять ping каждые 30 секунд
+        self.ping_timeout = 60   # Отключать если нет ответа 60 секунд
 
     async def connect(self, websocket: WebSocket, room_id: UUID, user_id: UUID):
         await websocket.accept()
         if room_id not in self.active_connections:
             self.active_connections[room_id] = set()
         self.active_connections[room_id].add((websocket, user_id))
+        # Инициализируем время последнего pong
+        self.last_pong[(room_id, user_id)] = time.time()
 
     def disconnect(self, websocket: WebSocket, room_id: UUID, user_id: UUID):
         if room_id in self.active_connections:
             self.active_connections[room_id].discard((websocket, user_id))
             if not self.active_connections[room_id]:
                 del self.active_connections[room_id]
+        # Удаляем запись о последнем pong
+        self.last_pong.pop((room_id, user_id), None)
+
+    def update_pong(self, room_id: UUID, user_id: UUID):
+        """Обновить время последнего pong от пользователя"""
+        self.last_pong[(room_id, user_id)] = time.time()
 
     async def broadcast_to_room(self, room_id: UUID, message: dict, exclude_user: UUID = None):
         if room_id not in self.active_connections:
@@ -39,10 +54,35 @@ class ConnectionManager:
         for conn in disconnected:
             self.active_connections[room_id].discard(conn)
 
+    async def send_to_user(self, room_id: UUID, user_id: UUID, message: dict):
+        """Отправить сообщение конкретному пользователю в комнате"""
+        if room_id not in self.active_connections:
+            return False
+
+        message_json = json.dumps(message, default=str)
+        for websocket, uid in self.active_connections[room_id]:
+            if uid == user_id:
+                try:
+                    await websocket.send_text(message_json)
+                    return True
+                except Exception:
+                    return False
+        return False
+
     def get_room_user_count(self, room_id: UUID) -> int:
         if room_id not in self.active_connections:
             return 0
         return len(self.active_connections[room_id])
 
+    def get_room_users(self, room_id: UUID) -> Set[UUID]:
+        """Получить список user_id в комнате"""
+        if room_id not in self.active_connections:
+            return set()
+        return {user_id for _, user_id in self.active_connections[room_id]}
+
+    def get_all_connections(self) -> Dict[UUID, Set[tuple[WebSocket, UUID]]]:
+        """Получить все активные соединения (для фоновой задачи пинга)"""
+        return self.active_connections
+
 
 manager = ConnectionManager()