Add missing invalidate method to codeCache - complete all missing methods

frontend/lib/caching/codeCache.ts

@@ -171,6 +171,14 @@ class CodeCache {
       totalMemoryUsage,
     };
   }
+
+  /**
+   * 특정 카테고리의 캐시 무효화
+   */
+  invalidate(category: string, companyCode?: string): boolean {
+    const cacheKey = this.createCodeKey(category, companyCode);
+    return this.delete(cacheKey);
+  }
 }
 
 // 싱글톤 인스턴스 생성