Proposal:Add MCP server

### Title

Model Context Protocol (MCP) Server for WinUI 3

### Summary

This proposal introduces a native Model Context Protocol (MCP) server for WinUI 3. It would provide a standardized bridge between the app and AI development agents. By exposing the visual tree, property system, and app lifecycle through a local stdio transport, agents can interact with live application state to assist with debugging, UI refactoring, and real-time prototyping.

### Rationale

Standardized AI Interop: Provides a consistent way for AI agents to "see" and "touch" WinUI 3 elements without brittle custom scripts.

Real-time UI Debugging: Allows developers to ask an agent to identify alignment issues or binding errors in the live visual tree, rather than relying on static XAML files.

Faster Prototyping: Enables "hot-editing" of UI properties via natural language commands during a live debug session.

Accessibility Verification: Agents can programmatically check the visual tree for proper AutomationPeer implementation and contrast ratios.

Reduced Cognitive Load: Automates the search for specific nodes across deeply nested XAML hierarchies in large codebases.

### Scope

### Important Notes

_No response_

### Open Questions

_No response_

The proposal identifies a native WinUI 3 MCP server using local stdio transport, but names no files, tests, or entry points and leaves the scope blank. Start by defining the supported visual-tree, property-system, and lifecycle operations, then establish the integration boundary and acceptance criteria before implementation.

Written by the indexing model from the issue text.