feat(auth): make upload review a separate grant instead of an admin privilege

Reviewing the upload queue is now a per-user flag (reviews_uploads), not part
of the admin role: several people can hold it, a moderator can have it, and an
admin may not. Only admins grant or revoke it; existing admins keep it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

services/api/internal/auth/handler.go

@@ -231,6 +231,7 @@ func MeDTO(u User) gen.Me {
 		Username:              u.Username,
 		DisplayName:           u.DisplayName,
 		Role:                  gen.Role(u.Role),
+		ReviewsUploads:        u.ReviewsUploads,
 		Locale:                u.Locale,
 		UiPrefs:               uiPrefsDTO(u.UIPrefs),
 		MustChangePassword:    u.MustChangePassword,