- Add comprehensive docstring to Proposal model documenting all relationships
- Add column comments for all fields (title, description, status, project_id, etc.)
- Mark feat_task_id as DEPRECATED (will be replaced by Essential→task mapping in BE-PR-008)
- Add proposal_code hybrid property as preferred alias for DB column propose_code
- Update ProposalResponse schema to include proposal_code alongside propose_code
- Update serializer to emit both proposal_code and propose_code for backward compat
- No DB migration needed — only Python-level changes
- Backend: new canonical Proposal model + /proposals router
- Backward-compat shims for old Propose imports and /proposes API
- Tests updated to use /proposals, legacy compat tests added
- Impact checklist: docs/BE-PR-001-rename-impact.md
- TASKLIST.md: BE-PR-001 marked complete
All 21 proposal tests pass.
