MCP: establish canonical read-only udos-mcp gateway

[fredporter]

Outcome

• migrates the only working stdio server to official MCP v2 server/client packages
• replaces twelve mixed/unsafe legacy tools with six bounded read-only owned adapters
• renames the package and source root to udos-mcp
• adds an end-to-end official-client protocol test with fixture APIs and schema rejection
• removes stale Python file-presence diagnostics and duplicate workspace MCP v1 dependencies
• aligns setup and architecture docs with implemented versus deferred contracts

Verification

• 487 backend tests passed
• 12 frontend tests passed
• frontend production build passed
• 3 udos-mcp protocol tests passed
• documentation, planning governance, duplicate-route audit, and diff checks passed