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/agents/workspace_manager.py

@@ -137,7 +137,7 @@ class RunWorkspaceManager:
         filename: str,
     ) -> str:
         """Load one run-scoped agent workspace file."""
-        path = self.get_agent_asset_dir(config_name, agent_id) / filename
+        path = self.skills_manager.get_agent_asset_dir(config_name, agent_id) / filename
         if not path.exists():
             raise FileNotFoundError(f"File not found: {filename}")
         return path.read_text(encoding="utf-8")
@@ -151,7 +151,7 @@ class RunWorkspaceManager:
         content: str,
     ) -> None:
         """Write one run-scoped agent workspace file."""
-        asset_dir = self.get_agent_asset_dir(config_name, agent_id)
+        asset_dir = self.skills_manager.get_agent_asset_dir(config_name, agent_id)
         asset_dir.mkdir(parents=True, exist_ok=True)
         path = asset_dir / filename
         path.write_text(content, encoding="utf-8")