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/plugins/fpw_proxy_list_download.py

@@ -0,0 +1,54 @@
+"""www.proxy-list.download 公开 API（README: Free_Proxy_Website）。"""
+from typing import List
+
+from app.core.plugin_system import ProxyRaw
+from app.plugins.base import BaseHTTPPlugin
+from app.core.log import logger
+
+
+class FpwProxyListDownloadPlugin(BaseHTTPPlugin):
+    name = "fpw_proxy_list_download"
+    display_name = "Proxy-List.download"
+    description = "proxy-list.download 官方 API（http/https/socks4/socks5）"
+
+    def __init__(self):
+        super().__init__()
+        self.max_concurrency = 8
+        self.api_pairs = [
+            ("http", "https://www.proxy-list.download/api/v1/get?type=http"),
+            ("https", "https://www.proxy-list.download/api/v1/get?type=https"),
+            ("socks4", "https://www.proxy-list.download/api/v1/get?type=socks4"),
+            ("socks5", "https://www.proxy-list.download/api/v1/get?type=socks5"),
+        ]
+        self.fallback_pairs = [
+            ("http", "https://api.proxyscrape.com/v2/?request=get&protocol=http&timeout=10000&country=all&ssl=all&anonymity=all"),
+            ("https", "https://api.proxyscrape.com/v2/?request=get&protocol=https&timeout=10000&country=all&ssl=all&anonymity=all"),
+            ("socks4", "https://api.proxyscrape.com/v2/?request=get&protocol=socks4&timeout=10000&country=all&ssl=all&anonymity=all"),
+            ("socks5", "https://api.proxyscrape.com/v2/?request=get&protocol=socks5&timeout=10000&country=all&ssl=all&anonymity=all"),
+        ]
+
+    async def crawl(self) -> List[ProxyRaw]:
+        results: List[ProxyRaw] = []
+        urls = [u for _, u in self.api_pairs]
+        htmls = await self.fetch_all(urls, timeout=10, retries=1)
+        for (protocol, _), text in zip(self.api_pairs, htmls):
+            if not text:
+                continue
+            batch = self.parse_text_proxies(text, protocol)
+            if batch:
+                results.extend(batch)
+                logger.info(f"{self.display_name} {protocol}: {len(batch)} 条")
+        if not results:
+            logger.warning(f"{self.display_name} 主 API 无数据，尝试 ProxyScrape 备用")
+            fb_urls = [u for _, u in self.fallback_pairs]
+            fb_htmls = await self.fetch_all(fb_urls, timeout=10, retries=1)
+            for (protocol, _), text in zip(self.fallback_pairs, fb_htmls):
+                if not text:
+                    continue
+                batch = self.parse_text_proxies(text, protocol)
+                if batch:
+                    results.extend(batch)
+                    logger.info(f"{self.display_name} fallback {protocol}: {len(batch)} 条")
+        if results:
+            logger.info(f"{self.display_name} 合计 {len(results)} 条")
+        return results