feat(mcp): Setup beads-mcp for PyPI distribution

Prepared the beads-mcp package for publishing to PyPI, simplifying installation
for users who want to use the MCP server with Claude Desktop or other MCP clients.

Changes:
- Added LICENSE file (MIT) to integrations/beads-mcp/
- Updated pyproject.toml with PyPI metadata (license, URLs, classifiers)
- Updated README with simplified installation (uv tool install beads-mcp)
- Created PYPI.md with detailed publishing guide
- Updated examples/claude-desktop-mcp/README to reference the production MCP server

Installation is now simplified from:
  git clone && cd && uv sync
to:
  uv tool install beads-mcp

Configuration is simplified from multi-line with --directory args to:
  "command": "beads-mcp"

Tested build successfully. Package ready for:
- Test PyPI: python -m twine upload --repository testpypi dist/*
- Production PyPI: python -m twine upload dist/*

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

integrations/beads-mcp/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2025 Beads Contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.