Design-phase foundation for v2 rotation. Changes NO credential at any service.
- internal/rotate: Rotator interface + registry + PlanAll (zero drivers
registered, so every credential plans as "(none)")
- internal/rotate.Snapshot: the MANDATORY backup gate — seals the gopass
prefix into an authenticated bundle, re-opens it, and confirms the entry
count matches before returning; any failure blocks rotation
- internal/sink.CountBundleRecords: read-only bundle completeness check
- cmd: `incredigo rotate` runs the backup gate + prints the plan; it is
dry-run only and refuses --execute (design phase)
- tests: backup gate happy path, no-overwrite, tamper detection; race-clean
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>