Move all MCP server declarations from individual plugin .mcp.json files
to a single .mcp.json at the marketplace root. This fixes MCP loading
failures where only one plugin's MCP would load.
- Add .mcp.json at marketplace root with all 5 servers
- Remove plugin-level .mcp.json files (projman, pr-review, cmdb-assistant,
data-platform, viz-platform, contract-validator)
- Update CLAUDE.md to reflect new architecture
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>