Wire UI consumer for mcp.json catalog

[samkeen]

Sub-issue of #10. Tracking the UI consumer for `catalog/mcp.json`.

State today

• Sync: `scripts/sync-mcp.js` runs on the weekly cron, writes `catalog/mcp.json` (3 installation scopes: Local / Project / User).
• Backend: round-trips through `read_catalog` as `mcp` on the wire.
• Frontend: nothing reads it. Declared as `mcp: unknown` in `src/lib/catalog.ts`.

Likely shape

Smallest surface of the 5. Natural fits:

• Tooltip / popover on the existing topbar managed-mcp pill — show where the user's MCP servers live (Local / Project / User), what each scope shares with the team, and where it's stored. Already called out in roadmap as a candidate.
• Drawer cross-reference for any future row that touches MCP scope.

Pick up only if there's a clear UX win — small surface and the catalog is just 3 records.

Related

• Umbrella: Surface synced catalogs that have no UI consumer yet #10
• Roadmap: `spec/roadmap.md` § "Inspector polish — Open work" (managed-mcp pill enrichment)
• Catalog shape: `spec/catalog-sync.md` § mcp