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_socks_ssl_proxy.py

@@ -0,0 +1,56 @@
+"""socks-proxy.net / sslproxies.org 表格（README 参考 GetProxyFromSocks-proxy.py）。"""
+import re
+from typing import List
+
+from app.core.plugin_system import ProxyRaw
+from app.plugins.base import BaseHTTPPlugin
+from app.core.log import logger
+
+
+class FpwSocksSslProxyPlugin(BaseHTTPPlugin):
+    name = "fpw_socks_ssl_proxy"
+    display_name = "Socks-Proxy / SSLProxies"
+    description = "socks-proxy.net 与 sslproxies.org 首页表格（HTTP/HTTPS 列表）"
+
+    def __init__(self):
+        super().__init__()
+        self.max_concurrency = 6
+        # 与 sslproxies 同模板的镜像站较多，socks-proxy 在部分网络下不稳定，多源提高成功率
+        self.urls = [
+            "https://www.sslproxies.org/",
+            "https://free-proxy-list.net/",
+            "https://www.us-proxy.org/",
+            "https://www.socks-proxy.net/",
+        ]
+
+    def _parse_page(self, html: str, default_protocol: str) -> List[ProxyRaw]:
+        results = []
+        pattern = re.compile(
+            r"(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})</td>\s*<td[^>]*>\s*(\d+)",
+            re.I,
+        )
+        for ip, port in pattern.findall(html):
+            if port.isdigit() and 1 <= int(port) <= 65535:
+                try:
+                    results.append(ProxyRaw(ip, int(port), default_protocol))
+                except ValueError:
+                    continue
+        return results
+
+    async def crawl(self) -> List[ProxyRaw]:
+        results: List[ProxyRaw] = []
+        htmls = await self.fetch_all(self.urls, timeout=12, retries=1)
+        for url, html in zip(self.urls, htmls):
+            if not html:
+                continue
+            if "socks-proxy" in url:
+                proto = "socks4"
+            else:
+                proto = "http"
+            batch = self._parse_page(html, proto)
+            results.extend(batch)
+            if batch:
+                logger.info(f"{self.display_name} {url}: {len(batch)} 条")
+        if results:
+            logger.info(f"{self.display_name} 合计 {len(results)} 条")
+        return results