feat: 기수 관리(조회,수정) 을 담당하는 AdminGenerationController 추가 (DASOMBE-16)

Author: junjinyun

src/main/java/dmu/dasom/api/global/admin/controller/AdminGenerationController.java

@@ -0,0 +1,34 @@
+package dmu.dasom.api.global.admin.controller;
+
+import dmu.dasom.api.global.generation.service.GenerationService;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.Parameter;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/api/admin")
+@RequiredArgsConstructor
+public class AdminGenerationController {
+
+    private final GenerationService generationService;
+
+    // 기수 조회
+    @Operation(summary = "현재 저장된 기수 조회")
+    @GetMapping("/generation")
+    public ResponseEntity<String> getCurrentGeneration() {
+        String currentGeneration = generationService.getCurrentGeneration();
+        return ResponseEntity.ok(currentGeneration);
+    }
+
+    // 기수 수정
+    @Operation(summary = "기수 수정")
+    @PatchMapping("/generation")
+    public ResponseEntity<Void> updateGeneration(
+            @RequestParam @Parameter(description = "새로운 기수 (예: '1기')") String generationValue
+    ) {
+        generationService.saveOrUpdateGeneration(generationValue);
+        return ResponseEntity.ok().build();
+    }
+}