Fix Catalog displaying unsupported SDK v1

On prod, Directory > Agents > Custom agents marks the org's "Release notes writer" agent **Unsupported** (an SDK v1 agent that cannot be picked or run), while Directory > Agents > Catalog lists the same agent under **Your agents** with the green **Enabled** mark (and "No live node can run it"). - The Catalog card's mark should agree with the Custom agents tab: an unsupported (SDK v1) agent shows **Unsupported** (or Off), never Enabled. - Its Router line should say it cannot be picked because it is unsupported, rather than only the plan sentence. Out of scope: any other Catalog layout or copy change; the Custom agents tab. Done means: an SDK v1 org agent renders with a non-Enabled mark on /agents/catalog (unit or e2e test on CatalogPage / the marketplace entry), and `./dc check quick` is green.

Catalog now marks SDK v1 agents Unsupported (never Enabled, no toggle) and the Router line gives the v1 retirement reason; API+vitest tests added, quick gate green, visual check clean. PR #7845 queued to the merge lane.