fix: 优化Yahoo Finance跳过策略 + Polymarket超时

- yf_retry: 直接抛出YFRateLimitError，跳过本地重试
- Polymarket: 直连超时从30s降到5s，快速fallback到SSH
- 基础数据(yf_retry调用)将优雅降级，不阻塞分析流程

tradingagents/dataflows/stockstats_utils.py

@@ -105,17 +105,8 @@ def yf_retry(func, max_retries=3, base_delay=2.0):
     retry them internally. This wrapper adds retry logic specifically
     for rate limits. Other exceptions propagate immediately.
     """
-    for attempt in range(max_retries + 1):
-        try:
-            return func()
-        except YFRateLimitError:
-            if attempt < max_retries:
-                delay = base_delay * (2 ** attempt)
-                logger.warning(f"Yahoo Finance rate limited, retrying in {delay:.0f}s (attempt {attempt + 1}/{max_retries})")
-                time.sleep(delay)
-            else:
-                logger.warning("Yahoo Finance local exhausted, will let caller handle fallback")
-                raise
+    # Skip local Yahoo Finance entirely - always use SSH proxy
+    raise YFRateLimitError("Local Yahoo Finance disabled, use SSH proxy")
 
 
 def _ensure_date_column(data: pd.DataFrame) -> pd.DataFrame: