feat(users, contents): extend admin update functionality and role management

- Added `moderator` role to `User` type for improved role assignment flexibility.
- Introduced `updateAdmin` method in user and content services to handle partial admin-specific updates.
- Enhanced `Content` type with `categoryId` and `iconUrl` to support richer categorization.

backend/src/users/dto/update-user.dto.ts

@@ -14,4 +14,12 @@ export class UpdateUserDto {
 	@IsOptional()
 	@IsString()
 	avatarUrl?: string;
+
+	@IsOptional()
+	@IsString()
+	status?: "active" | "verification" | "suspended" | "pending" | "deleted";
+
+	@IsOptional()
+	@IsString()
+	role?: string;
 }