Adds the structured error code returned when a rename rolls back because a
referenced transcription block was edited concurrently (OptimisticLockException
on transcription_blocks.version). Mirrors the contract in
frontend src/lib/errors.ts and adds the localised message keys
error_person_rename_conflict in de/en/es so the UI surfaces a retry hint
instead of a generic 500.
The actual translation of OptimisticLockException → DomainException
(PERSON_RENAME_CONFLICT) lands in the next commit alongside the integration
test that proves the rollback semantics.
Refs #362
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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