Permanently delete an image generator

Permanently and immediately erase a caller-owned scope=user image generator. The generator, all its versions (provider config, model, parameters), all run records, and all anonymous run records are removed from the live system at once. There is no recovery path. Use DELETE /{generator_id} (revoke) to deactivate without erasing, keeping the audit trail intact. Serving gate: if any live published template version carries a snapshot that references this generator, deletion is refused (409). Unpublish the relevant template version(s) first, then retry. Platform scope=system generators and another user's generators always surface as 404. Encrypted backups age out within the platform's standard retention window (up to three months), so the data is not instantly erased from all systems everywhere, but it is no longer accessible through any product surface after this call. Returns {generator_id, name, deleted: true}.