Manager reset-selected endpoint to restore chapter assignments to not_started (Maestro fixture baseline) #464

Summary

Add a manager-only endpoint that restores selected chapter assignments to not_started so Maestro ownership fixtures can reclaim burned claim chapters without rotating to a new chapter or wiping the fixture project.

Unblocks eten-tech-foundation/fluent-mobile#607 (claim baseline restore). Conflict and open Peer Check seeds for that ticket use existing endpoints and do not need this change.

Proposed contract

PATCH /projects/{projectId}/chapter-assignments/reset-selected

Body: { chapterAssignmentIds: int[] }

For each listed chapter:

• set status to not_started
• set assignedUserId and peerCheckerId to null
• set submittedTime to null
• write status/assignment history (recordStatusChange)

Scope:

• Middleware matches assign-selected: CONTENT_ASSIGN + project UPDATE
• Only chapters currently in draft or peer_check may be reset
• Any other status returns 409
• Ids not in the project return 404
• Reuse MAX_CHAPTER_ASSIGNMENTS_PER_REQUEST and the assign-selected error shape

Acceptance criteria

• Manager can reset draft and peer_check chapters to not_started and unassigned
• Non-manager receives 403
• Chapters past peer_check (or any other status) receive 409
• Ids outside the project receive 404
• Status history is written
• A reset chapter can be claimed again
• docs/permissions.md documents the new policy

Implementation notes

Reuse updateChapterAssignment(..., tx) so FA-R6 history is written. Widen UpdateChapterAssignmentRequestData.submittedTime to Date | null (FA-R9). Add resetStatus on chapter-assignments.policy.ts.

Links

• fluent-mobile #607