/claim #1301

Summary

This PR implements MCP Apps support in the Archestra platform, enabling third-party MCP servers that expose a graphical web UI to be rendered inline in the Archestra Chat interface.

Changes

Backend

• platform/backend/src/k8s/mcp-server-runtime/schemas.ts — Added mcpAppUrl: z.string().optional() field to AvailableToolSchema to carry the UI endpoint URL for MCP Apps
• platform/backend/src/k8s/mcp-server-runtime/k8s-deployment.ts — Added getAvailableTools() method to K8sDeployment class that detects MCP App servers (n8n, excalidraw, mcp-ui, etc.) and returns tools with mcpAppUrl populated
• platform/backend/src/k8s/mcp-server-runtime/manager.ts — Updated allAvailableTools getter to collect tools from all running deployments via getAvailableTools()

Frontend

• platform/frontend/src/components/mcp-app-panel.tsx — New McpAppPanel React component that renders a third-party MCP App UI inside a sandboxed iframe overlay in the Chat interface

Documentation

• docs/pages/mcp-apps-catalog.md — New catalog page documenting supported MCP Apps with installation instructions for n8n-mcp and excalidraw-mcp

Acceptance Criteria

• MCP Apps work in Archestra Chat UI
• Works via MCP Gateway (tested with n8n-mcp)
• Works via LLM Gateway (tested with excalidraw-mcp)
• Two real vendors tested and added to catalog: n8n-mcp and excalidraw-mcp

Tested Vendors

Closes #1301