feat: SSH连接池串行化 + Polymarket/数据源统一走连接池

- 新增ssh_proxy_pool.py: 全局单例连接池，队列串行化SSH请求
- stockstats_utils.py: _fetch_via_ssh改用连接池
- polymarket.py: 跳过本地直接走SSH连接池
- 消除并发SSH资源竞争问题

tradingagents/dataflows/ssh_proxy_pool.py

@@ -0,0 +1,123 @@
+"""SSH Proxy Connection Pool — 串行化所有SSH中转请求，避免并发资源竞争。
+
+所有需要走中转的数据源统一调用 ssh_proxy_fetch(url)，
+内部通过队列串行化SSH连接，避免多线程/多进程并发导致的连接冲突。
+"""
+import json
+import logging
+import subprocess
+import threading
+import time
+from queue import Queue, Empty
+from typing import Optional
+
+logger = logging.getLogger(__name__)
+
+# SSH配置缓存
+_ssh_config: Optional[tuple] = None
+_config_lock = threading.Lock()
+
+
+def _get_ssh_config() -> tuple:
+    """获取SSH配置（host, port, password），带缓存。"""
+    global _ssh_config
+    if _ssh_config is not None:
+        return _ssh_config
+    with _config_lock:
+        if _ssh_config is not None:
+            return _ssh_config
+        from .stockstats_utils import _get_ssh_config as _load_config
+        _ssh_config = _load_config()
+        return _ssh_config
+
+
+class SSHProxyPool:
+    """SSH代理连接池 — 串行化所有SSH请求。"""
+    
+    def __init__(self):
+        self._queue = Queue()
+        self._lock = threading.Lock()
+        self._initialized = False
+    
+    def _ensure_initialized(self):
+        """确保连接池已初始化。"""
+        if self._initialized:
+            return
+        with self._lock:
+            if self._initialized:
+                return
+            # 放一个占位符，表示可以发起请求
+            self._queue.put(True)
+            self._initialized = True
+    
+    def fetch(self, url: str, timeout: int = 30) -> str:
+        """通过SSH代理获取URL内容，串行化执行。
+        
+        Args:
+            url: 要获取的URL
+            timeout: 超时时间（秒）
+        
+        Returns:
+            URL响应内容字符串
+        
+        Raises:
+            RuntimeError: SSH代理失败时抛出
+        """
+        self._ensure_initialized()
+        
+        # 等待轮到自己（最多等timeout秒）
+        try:
+            self._queue.get(timeout=timeout)
+        except Empty:
+            raise RuntimeError(f"SSH proxy queue timeout after {timeout}s")
+        
+        try:
+            host, port, password = _get_ssh_config()
+            cmd = [
+                "sshpass", "-p", password,
+                "ssh", "-o", "StrictHostKeyChecking=no",
+                "-o", "ConnectTimeout=15",
+                "-o", "ServerAliveInterval=10",
+                "-p", str(port), f"root@{host}",
+                f'curl -sL --max-time {timeout} "{url}"'
+            ]
+            result = subprocess.run(
+                cmd, capture_output=True, text=True, 
+                timeout=timeout + 10  # 给SSH额外时间
+            )
+            
+            if result.returncode != 0:
+                raise RuntimeError(f"SSH proxy failed (rc={result.returncode}): {result.stderr[:200]}")
+            
+            if not result.stdout or not result.stdout.strip():
+                raise RuntimeError("SSH proxy returned empty response")
+            
+            return result.stdout
+            
+        except subprocess.TimeoutExpired:
+            raise RuntimeError(f"SSH proxy subprocess timeout after {timeout}s")
+        finally:
+            # 无论成功失败，都放回占位符，让下一个请求执行
+            self._queue.put(True)
+    
+    def fetch_json(self, url: str, timeout: int = 30) -> dict:
+        """通过SSH代理获取JSON响应。"""
+        text = self.fetch(url, timeout)
+        try:
+            return json.loads(text)
+        except json.JSONDecodeError as e:
+            raise RuntimeError(f"SSH proxy returned invalid JSON: {e}")
+
+
+# 全局单例
+_pool = SSHProxyPool()
+
+
+def ssh_proxy_fetch(url: str, timeout: int = 30) -> str:
+    """通过SSH代理获取URL内容（串行化）。"""
+    return _pool.fetch(url, timeout)
+
+
+def ssh_proxy_fetch_json(url: str, timeout: int = 30) -> dict:
+    """通过SSH代理获取JSON响应（串行化）。"""
+    return _pool.fetch_json(url, timeout)