feat: Connect Mission Control dashboard to OpenClaw Gateway API

- Add OpenClawGatewayClient (HTTP polling every 30s)
- Add useOpenClaw hook for React integration
- Update MissionControlDashboard to use live agent data
- Update StatusBar to show gateway health, sessions, connection status
- Update AgentDetailPanel to accept live events
- Add .env.example for gateway configuration
- Remove dist/ from git (build artifact)

.gitignore

@@ -0,0 +1,16 @@
+# Build output
+dist/
+
+# Dependencies
+node_modules/
+
+# Environment
+.env
+.env.local
+
+# Build info
+*.tsbuildinfo
+
+# OS
+.DS_Store
+Thumbs.db