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_checkerproxy.py

@@ -0,0 +1,65 @@
+"""checkerproxy.net：尝试常见导出路径 + 正文中的 ip:port（排除示例占位）。"""
+import re
+from typing import List, Set, Tuple
+
+from app.core.plugin_system import ProxyRaw
+from app.plugins.base import BaseHTTPPlugin
+from app.core.log import logger
+
+
+class FpwCheckerproxyPlugin(BaseHTTPPlugin):
+    name = "fpw_checkerproxy"
+    display_name = "CheckerProxy.net"
+    description = "checkerproxy.net（无稳定公开 API 时可能为空；多路径尝试）"
+
+    def __init__(self):
+        super().__init__()
+        self.urls = [
+            "https://checkerproxy.net/",
+            "https://checkerproxy.net/export",
+            "https://checkerproxy.net/api/export",
+        ]
+
+    @staticmethod
+    def _parse_ip_ports(text: str) -> List[ProxyRaw]:
+        bad = {"123.123.123.123", "127.0.0.1", "0.0.0.0"}
+        seen: Set[Tuple[str, int]] = set()
+        out: List[ProxyRaw] = []
+        for m in re.finditer(
+            r"\b(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}):(\d{2,5})\b",
+            text,
+        ):
+            ip, ps = m.group(1), m.group(2)
+            if ip in bad:
+                continue
+            if not ps.isdigit() or not (1 <= int(ps) <= 65535):
+                continue
+            key = (ip, int(ps))
+            if key in seen:
+                continue
+            seen.add(key)
+            try:
+                out.append(ProxyRaw(ip, int(ps), "http"))
+            except ValueError:
+                continue
+        return out
+
+    async def crawl(self) -> List[ProxyRaw]:
+        merged: List[ProxyRaw] = []
+        seen: Set[Tuple[str, int, str]] = set()
+        htmls = await self.fetch_all(self.urls, timeout=12, retries=1)
+        for html in htmls:
+            if not html or len(html) < 200:
+                continue
+            for p in self._parse_ip_ports(html):
+                k = (p.ip, p.port, p.protocol)
+                if k not in seen:
+                    seen.add(k)
+                    merged.append(p)
+            if len(merged) >= 50:
+                break
+        if merged:
+            logger.info(f"{self.display_name} 解析 {len(merged)} 条")
+        else:
+            logger.warning(f"{self.display_name} 未解析到代理（站点可能仅提供在线检测）")
+        return merged