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/polymarket.py

@@ -13,11 +13,9 @@ import json
 import logging
 from datetime import datetime, timezone
 
-import subprocess
-
 import requests
 
-from .stockstats_utils import _get_ssh_config
+from .ssh_proxy_pool import ssh_proxy_fetch_json
 
 logger = logging.getLogger(__name__)
 
@@ -35,35 +33,10 @@ DEFAULT_LIMIT = 6
 
 def _request(path: str, params: dict) -> dict:
     url = f"{GAMMA_BASE}/{path}"
-    try:
-        response = requests.get(url, params=params, timeout=DIRECT_TIMEOUT)
-        response.raise_for_status()
-        return response.json()
-    except requests.RequestException:
-        # Fallback: fetch through SSH proxy
-        logger.info("Polymarket direct failed, trying SSH proxy for %s...", path)
-        query = "&".join(f"{k}={v}" for k, v in params.items())
-        full_url = f"{url}?{query}"
-        host, port, password = _get_ssh_config()
-        cmd = [
-            "sshpass", "-p", password,
-            "ssh", "-o", "StrictHostKeyChecking=no",
-            "-o", "ConnectTimeout=15",
-            "-p", str(port), f"root@{host}",
-            f'curl -s "{full_url}"'
-        ]
-        try:
-            result = subprocess.run(cmd, capture_output=True, text=True, timeout=REQUEST_TIMEOUT)
-        except subprocess.TimeoutExpired:
-            raise requests.RequestException("SSH proxy timed out")
-        if result.returncode != 0:
-            raise requests.RequestException(f"SSH proxy failed: {result.stderr}")
-        if not result.stdout or not result.stdout.strip():
-            raise requests.RequestException("SSH proxy returned empty response")
-        try:
-            return json.loads(result.stdout)
-        except json.JSONDecodeError as e:
-            raise requests.RequestException(f"SSH proxy returned invalid JSON: {e}")
+    # Skip local request, go directly through SSH proxy
+    query = "&".join(f"{k}={v}" for k, v in params.items())
+    full_url = f"{url}?{query}"
+    return ssh_proxy_fetch_json(full_url, timeout=REQUEST_TIMEOUT)
 
 
 def _parse_json_list(value) -> list: