feat: fpw plugins, validation/crawl perf, WS stats, test DB isolation

- Add Free_Proxy_Website-style fpw_* plugins and register them
- Per-plugin crawl timeout (crawl_timeout_seconds=120); remove global crawl_timeout setting
- Validator: fix connect vs total timeout on save; SOCKS session LRU cache; drop redundant semaphore
- Validation handler uses single DB connection; batch upsert after crawl; WorkerPool put_nowait
- Remove unused max_retries from settings API/UI; settings maintenance SQL + init_db cleanup of deprecated keys
- WebSocket dashboard stats; ProxyList pool_filter and API alignment
- POST /api/proxies/delete-one for IPv6-safe deletes; task poll stops on 404
- pytest uses PROXYPOOL_DB_PATH=db/proxies.test.sqlite so tests do not wipe production DB
- .gitignore: explicit proxies.test.sqlite patterns; fix plugin_service ValidationException import

Made-with: Cursor

app/api/ws_manager.py

@@ -0,0 +1,52 @@
+"""WebSocket 连接管理与广播"""
+import asyncio
+from typing import List
+
+from starlette.websockets import WebSocket, WebSocketState
+
+
+class ConnectionManager:
+    def __init__(self) -> None:
+        self._connections: List[WebSocket] = []
+        self._lock = asyncio.Lock()
+
+    @property
+    def connection_count(self) -> int:
+        return len(self._connections)
+
+    async def connect(self, websocket: WebSocket) -> None:
+        async with self._lock:
+            self._connections.append(websocket)
+
+    async def disconnect(self, websocket: WebSocket) -> None:
+        async with self._lock:
+            if websocket in self._connections:
+                self._connections.remove(websocket)
+
+    async def broadcast_json(self, payload: dict) -> None:
+        async with self._lock:
+            targets = list(self._connections)
+        stale: List[WebSocket] = []
+        for ws in targets:
+            try:
+                if ws.client_state != WebSocketState.CONNECTED:
+                    stale.append(ws)
+                    continue
+                await ws.send_json(payload)
+            except Exception:
+                stale.append(ws)
+        if stale:
+            async with self._lock:
+                for ws in stale:
+                    if ws in self._connections:
+                        self._connections.remove(ws)
+
+    async def disconnect_all(self) -> None:
+        async with self._lock:
+            targets = list(self._connections)
+            self._connections.clear()
+        for ws in targets:
+            try:
+                await ws.close()
+            except Exception:
+                pass