[Feature] Extend Baked Image & Repave (M1) to the bounded Step/Runner controller

Problem

M1 (#223) shipped a working baked-image + repave implementation, but it lived entirely inside the old monolithic dbinstance_controller.go. PR #241, merged the same day, restructured the controller into bounded per-step internal/ensure/*.go files under a Step/Runner chain and removed spec.osImage/AppliedSpec.OSImage — the field the M1 catalog was keyed off. None of M1's controller-side wiring survived: no repave step, no drift conditions/annotation, no catalog in the new tree. Three files in internal/ensure/ still reference the removed field as dead code.

Solution overview

Extend M1's design onto the current Step/Runner architecture — same mechanism (pre-built Harvester images via Packer, cloud-init activates one PostgreSQL version, repave swaps the OS disk in place with pgdata untouched), same "tenant sets engineVersion only, OS stream is an ops-controlled platform default" split from the original RFC. Full design doc and decision log: my-docs/Baked-Image-newCRD/P003-final-plan.md.

Notable deltas from M1 (see linked #168 update for the full list and rationale): merged ConditionImageDrift (was two condition types); catalog moved to internal/catalog; OS/data disk PVC names carry an 8-hex-char UID slice to prevent leaked-disk reattachment on recreate; images bake every supported PG major version side by side and engineVersion now actually drives which one boots.

Completion checklist

• Config, catalog, RBAC, and CRD/condition surface — databaseDefaults.osVersion, internal/catalog (BakedImages/LatestBakedImages), PVC RBAC, ConditionImageDrift/ConditionRepaveInProgress + print columns
• Harvester client support — SwapVMOSDisk/DeletePVC on ClientInterface/TypedClient/StubHarvester
• Controller wiring — preflight/vm resolve against the catalog, dead OSImage refs removed, internal/ensure/repave.go step added to the reconcile chain
• Packer pipeline realigned with feature-imagebaking; full local test pass (unit + envtest) green
• Build, upload, and register the first real image in the catalog
• Real-cluster verification (database/test/repave-e2e.sh, including the PG-version-EOL stage)
• Documentation housekeeping (databaseDefaults.osVersion documented where an operator would find it)
• Open PR — Closes #252, references the design update on #168

Testing

database/test/repave-e2e.sh — stage-based end-to-end runner against a real Harvester cluster (provisioning, drift detection, repave, teardown, PG EOL scenarios). Unit tests cover controller/catalog/harvester-client logic independently.