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/services/proxy_service.py

@@ -30,10 +30,19 @@ class ProxyService:
         max_score: Optional[int] = None,
         sort_by: str = "last_check",
         sort_order: str = "DESC",
+        pool_filter: Optional[str] = None,
     ) -> Tuple[List[Proxy], int]:
         async with get_db() as db:
             return await self.proxy_repo.list_paginated(
-                db, page, page_size, protocol, min_score, max_score, sort_by, sort_order
+                db,
+                page,
+                page_size,
+                protocol,
+                min_score,
+                max_score,
+                sort_by,
+                sort_order,
+                pool_filter=pool_filter,
             )
 
     async def get_random_proxy(self) -> Optional[Proxy]:
@@ -72,7 +81,9 @@ class ProxyService:
 
         exported = 0
         async with get_db() as db:
-            async for batch in self.proxy_repo.iter_batches(db, protocol=protocol, batch_size=1000):
+            async for batch in self.proxy_repo.iter_batches(
+                db, protocol=protocol, batch_size=1000, only_usable=True
+            ):
                 for p in batch:
                     if exported >= limit:
                         break