feat: add MCP server with resources, tools, auth, and Traefik routing

- Add backend/app/mcp_server.py with FastMCP server (hms-cms)
- Resources: design-rules, page-structure, sync-status
- Tools: trigger_sync, get_sync_log, set_rentman_token, read_file,
  write_file, create_page, deploy, git_commit, git_status
- Bearer token auth via MCP_AUTH_TOKEN env var
- Mount MCP at /mcp with streamable HTTP transport
- Integrate session manager in FastAPI lifespan
- Add Traefik labels for external /mcp route on hms.media-on.de
- Add git, docker.io, curl to backend Dockerfile
- Mount repo root + docker socket in backend container
- Add mcp>=1.0.0 to requirements.txt

frontend/src/components/EmptyState.tsx

@@ -0,0 +1,18 @@
+interface Props {
+  icon?: string;
+  title: string;
+  message: string;
+  actionLabel?: string;
+  onAction?: () => void;
+}
+
+export default function EmptyState({ icon = '🔍', title, message, actionLabel, onAction }: Props) {
+  return (
+    <div className="text-center py-16 px-4" role="status">
+      <div className="text-6xl mb-4" aria-hidden="true">{icon}</div>
+      <h3 className="text-xl font-semibold mb-2" style={{ color: 'var(--text)' }}>{title}</h3>
+      <p className="max-w-md mx-auto mb-6" style={{ color: 'var(--secondary)' }}>{message}</p>
+      {actionLabel && <button onClick={onAction} className="hms-btn hms-btn-primary">{actionLabel}</button>}
+    </div>
+  );
+}