feat: OpenClaw WebSocket integration with workspace file preview

- Migrate OpenClaw from HTTP (port 8004) to WebSocket (port 18789)
- Add workspace file list and content preview handlers
- Add OpenClawStatus component with agent/skills view
- Add OpenClawView panel in trader interface
- Add Zustand store for OpenClaw state management
- Fix gateway logging noise (yfinance, websockets)
- Fix RunWorkspaceManager.get_agent_asset_dir attribute error
- Handle missing workspace files gracefully in preview

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/gateway_server.py

@@ -72,14 +72,16 @@ class SuppressNoisyInfoFilter(logging.Filter):
     """Filter out low-signal library INFO logs while keeping warnings/errors."""
 
     def filter(self, record: logging.LogRecord) -> bool:
-        if record.levelno >= logging.WARNING:
-            return True
-
         message = record.getMessage()
         if record.name == "httpx" and message.startswith("HTTP Request:"):
             return False
         if record.name.startswith("websockets") and "connection open" in message:
             return False
+        if record.name.startswith("websockets") and "opening handshake failed" in message:
+            return False
+
+        if record.levelno >= logging.WARNING:
+            return True
 
         return True