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

tests/task_utils.py

@@ -0,0 +1,22 @@
+"""测试用异步任务轮询工具"""
+import asyncio
+from typing import Any, Dict, Optional
+
+
+async def poll_task_until_terminal(
+    client,
+    task_id: str,
+    *,
+    max_rounds: int,
+    interval: float,
+) -> Optional[Dict[str, Any]]:
+    """轮询任务直到终态或超时。返回最后一次 task data。"""
+    task_data = None
+    for _ in range(max_rounds):
+        await asyncio.sleep(interval)
+        res = await client.get(f"/api/tasks/{task_id}")
+        assert res.status_code == 200
+        task_data = res.json()["data"]
+        if task_data["status"] in ("completed", "failed", "cancelled"):
+            break
+    return task_data