- New router: /projects/{project_id}/proposals/{proposal_id}/essentials
- GET (list), POST (create), GET/{id}, PATCH/{id}, DELETE/{id}
- All mutations restricted to open proposals only
- Permission: creator, project owner, or global admin
- Registered essentials router in main.py
- Updated GET /proposals/{id} to return ProposalDetailResponse with
embedded essentials list
- Activity logging on all CRUD operations
