Summary

Implements @mcp-ui/client to render rich interactive UI components directly from MCP tool outputs in the chat interface.

Changes

• New McpUiToolOutput component — uses UIResourceRenderer from @mcp-ui/client to render interactive UI from MCP tool responses
• Updated chat-messages.tsx — detects mcp-ui resource type in tool outputs and renders with McpUiToolOutput, falls back to standard ToolOutput for regular responses
• Test MCP servers — includes weather-mcp.js and poll-mcp.js demo servers showing interactive outputs

How it works

When a MCP tool returns a response with type resource and a mcp-ui:// URI, the chat renders it as a live interactive component instead of raw JSON. Non-UI tool outputs continue to render as before.

/claim #1301