Copilot Chat MCP support addition

[sahilk873]

This update makes the existing ShortKit-ML MCP server usable from GitHub Copilot Chat in VS Code without changing the detector code itself.

The gap in issue #3 was not the shortcut-detection API. The repo already exposed the full MCP tool surface, but it did not ship a VS Code workspace config or documented Copilot Chat flow. As a result, Copilot users had no checked-in path to discover and launch the shortkit-ml server from the repo.

This change adds a tracked .vscode/mcp.json using the same shortcut_detect.mcp_server entry point as the Claude Code/Desktop setup, documents the VS Code Agent-mode workflow in docs/mcp-server.md, and updates the README MCP section to mention GitHub Copilot in VS Code. I also added a small regression test that keeps the VS Code MCP config aligned with the root project config.

Validation:

• pytest -q tests/test_mcp_server.py tests/test_copilot_mcp_config.py
• python3 -m json.tool .vscode/mcp.json
• python3 -m json.tool .mcp.json

Notes:

• This is a repo-side Copilot Chat integration via MCP, not a GitHub App extension. That matches the current documented Copilot/MCP path and keeps the server on a maintained integration surface.

Closes #3.