feat(contents): enhance user-specific data handling and admin content management

Integrate user-specific fields (`isLiked`, `favoritesCount`) in content APIs and improve `ContentCard` through reactive updates. Add admin-only content deletion support. Refactor services and repository to enrich responses with additional data (author details, tags).

frontend/src/services/content.service.ts

@@ -61,4 +61,8 @@ export const ContentService = {
 		});
 		return data;
 	},
+
+	async removeAdmin(id: string): Promise<void> {
+		await api.delete(`/contents/${id}/admin`);
+	},
 };