- Add "Đổi mật khẩu" toggle in staff edit form with new password
and confirm password fields, validation (min 8 chars, match check)
- Add ResetStaffPasswordAsync() in PosDataService
- Add POST /api/bff/staff/reset-password BFF endpoint proxying to
IAM service /api/v1/users/{userId}/reset-password
- Reset password state fields when opening edit form
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>