Repair empty provider catalogs

[zrm625]

What changed

• stale-mark migrated Google and Microsoft connections whose per-service tools are missing
• refetch and persist a provider OpenAPI catalog when a migrated connection resolves against an empty operation store
• include configured connections with zero current tools in the toolkit editor
• cover SQLite migrations, provider catalog repair, and the self-host toolkit UI journey

Why

Provider-service migrations could leave valid connections marked as synchronized even though their service operation catalogs and tool rows were absent. Those connections then remained invisible or unusable instead of repairing through the normal catalog read path.

Validation

• changed-file formatter check
• bun run lint
• bun run typecheck
• bun run test
• bun run test:selfhost -- selfhost/toolkits-ui.test.ts
• scoped provider-split, OpenAPI, toolkit, and host migration tests