Edit ONE Series Bible character, not the whole array.

Changes only the fields in content on one character (found by id, or any name the Bible or the cast canon knows them by) and leaves every other character exactly as stored, under the same lock as every Bible save. expectedVersion (the currentVersion you read) makes it a compare-and-swap: when the Bible changed since, nothing is saved and it is a 409 series_bible_version_conflict. create: true adds the character when nobody answers to the name (else 404 character_not_found). A note about how someone LOOKS belongs on PATCH /story-projects/{projectId}/cast-look, which never touches the Bible. Every save returns gateChange { before, after, staleCoverage }: what it did to the project's gate. Appending (episodes for a new season, a new character) never re-locks anything. An edit to canon a coverage report scored puts that report out of date (staleCoverage) and re-locks what it opened: after full coverage, paid work on every episode already written (coverage, casting, table reads, videos, decks, trailers, publishing) until full coverage passes again. When after.stage comes before before.stage, tell the user. Free. Scope: story:write.