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/realtime.py

@@ -0,0 +1,25 @@
+"""实时统计广播后台任务"""
+import asyncio
+
+from fastapi import FastAPI
+
+from app.core.config import settings
+from app.core.log import logger
+from app.services.dashboard_stats import get_dashboard_stats
+
+
+async def stats_broadcaster_loop(app: FastAPI) -> None:
+    manager = app.state.ws_manager
+    interval = settings.ws_stats_interval_seconds
+    while True:
+        try:
+            await asyncio.sleep(interval)
+            if manager.connection_count == 0:
+                continue
+            scheduler = app.state.scheduler
+            stats = await get_dashboard_stats(scheduler.running)
+            await manager.broadcast_json({"type": "stats", "data": stats})
+        except asyncio.CancelledError:
+            break
+        except Exception:
+            logger.exception("stats broadcaster tick failed")