- Add POST /api/v1/admin/tools/{id}/request-changes endpoint
- Sets moderation_status to 'changes_requested' with feedback
- Extend /me/tools/{name}/status to return feedback when status is
changes_requested or rejected
- Add Request Changes button and modal in admin pending UI
- Make changes modal draggable like other modals
This allows admins to send feedback to publishers instead of just
approving or rejecting tools outright.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>