feat: 컨텐츠 전체 조회 API 헤더에 중국어, 일본어 추가

src/main/java/com/gsm/blabla/content/api/ContentControllerV2.java

@@ -0,0 +1,34 @@
+package com.gsm.blabla.content.api;
+
+import com.gsm.blabla.content.application.ContentService;
+import com.gsm.blabla.content.dto.ContentsResponseDto;
+import com.gsm.blabla.global.response.DataResponseDto;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import jakarta.validation.constraints.Pattern;
+import java.util.List;
+import java.util.Map;
+import lombok.RequiredArgsConstructor;
+import org.springframework.validation.annotation.Validated;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestHeader;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@Validated
+@Tag(name = "컨텐츠 관련 API")
+@RestController
+@RequestMapping("/api/v2/contents")
+@RequiredArgsConstructor
+public class ContentControllerV2 {
+
+    private final ContentService contentService;
+
+    @Operation(summary = "컨텐츠 전체 조회 API")
+    @GetMapping("")
+    public DataResponseDto<Map<String, List<ContentsResponseDto>>> getContents(
+        @Pattern(regexp = "^(ko|en|cn|jp)$", message = "언어는 ko 또는 en 중 하나여야 합니다.")
+        @RequestHeader(name="Content-Language") String language) {
+        return DataResponseDto.of(contentService.getContents(language));
+    }
+}