Set disabled to false in generated OpenCode V2 registrations so a
lower-priority disabled entry cannot keep approved setup stale.
Cover layered JSON/JSONC refreshes, idempotent setup and doctor readiness,
exact backups, preserved lower settings, malformed-config refusal, and
the exclusion of disabled registrations from automatic maintenance.
Update the native V2 registration expectations.
Fixes#3318
Haoran Xu