Maintain Connector Summary Read Model

GET /_ref/connectors is a core owner-console read path. Recent performance tranches made it fast by adding a short in-process cache and by making overview rows shallow, but that is not the final construction: the read path still has a large per-connection evidence fan-out underneath the cache, and record-ingest writes do not event-invalidate the summary projection.

accelerate-connection-summary-projection improved live performance with a 5-second cache and a shallow overview read. That was a safe tranche, not the SLVP-ideal construction. The remaining issue is architectural: the un-cached projection performs many reads per connection, while the cache freezes now-relative health/verdict copy and is not invalidated by record ingest.

The reference implementation SHALL maintain durable connector-summary evidence in a read model rather than recomputing every durable evidence input through a per-connection fan-out on each full-list read. The read model SHALL support SQLite and Postgres with equivalent schema, dirty marking, lazy reconciliation, and full rebuild or repair.