STATE-WP-0062 T5: docs, first-party↔repo test, mark workplan finished

- Add /docs/services reference (two-dimension model, persistence, API) and a
  pointer note from /docs/tpsc; add it to the Reference nav.
- Add a test asserting first_party.repo_slug resolves to a managed_repos FK
  (8 services tests green).
- Mark STATE-WP-0062 tasks done / status finished.

Known classes seeded in the live catalog via the API (Gitea, Postgres as
self-hosted/third-party; State Hub as self-hosted/first-party at Level 2).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

dashboard/observablehq.config.js

@@ -113,6 +113,7 @@ export default {
         { name: "Repos",                    path: "/docs/repos" },
         { name: "SBOM",                     path: "/docs/sbom" },
         { name: "SCOPE.md",                 path: "/docs/scope" },
+        { name: "Service Catalog",          path: "/docs/services" },
         { name: "Tasks",                    path: "/docs/tasks" },
         { name: "TPSC",                     path: "/docs/tpsc" },
         { name: "TPSC — GDPR Maturity",     path: "/docs/gdpr-maturity" },