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/core/plugin_system/base.py

@@ -18,6 +18,8 @@ class BaseCrawlerPlugin(ABC):
     description: str = ""
     enabled: bool = True
     default_config: Dict[str, Any] = {}
+    #: 单插件整段 crawl() 的 asyncio.wait_for 上限（秒），彼此独立、互不影响
+    crawl_timeout_seconds: float = 120.0
 
     def __init__(self):
         self._config: Dict[str, Any] = dict(self.default_config or {})