Return the full MCP tool catalog for the authenticated tenant.
The catalog is tenant-agnostic in v1 — every tenant sees the
same 12 canonical tools seeded by Plan 01 — but we still require
authentication so anonymous callers can’t enumerate capabilities.
Pass-through of :meth:MCPToolRegistry.list_tools. The outer
shape matches the MCP protocol tools/list response so the
frontend can render catalog entries directly.