feat: 휴가 부여현황 API 추가

- leave_grants 테이블 마이그레이션 추가
- LeaveGrant 모델 생성 (annual/monthly/reward/condolence/other 유형)
- LeaveService에 getGrants, storeGrant, destroyGrant 메서드 추가
- LeaveController에 grants, storeGrant, destroyGrant 엔드포인트 추가
- GET/POST/DELETE /api/v1/leaves/grants 라우트 추가
- 연차/월차 부여 시 LeaveBalance total_days 자동 갱신

app/Http/Controllers/Api/V1/LeaveController.php

@@ -154,4 +154,37 @@ public function setBalance(BalanceRequest $request): JsonResponse
             );
         }, __('message.updated'));
     }
+
+    /**
+     * 휴가 부여 이력 목록
+     * GET /v1/leaves/grants
+     */
+    public function grants(Request $request): JsonResponse
+    {
+        return ApiResponse::handle(function () use ($request) {
+            return $this->service->getGrants($request->all());
+        }, __('message.fetched'));
+    }
+
+    /**
+     * 휴가 부여
+     * POST /v1/leaves/grants
+     */
+    public function storeGrant(Request $request): JsonResponse
+    {
+        return ApiResponse::handle(function () use ($request) {
+            return $this->service->storeGrant($request->all());
+        }, __('message.leave.granted'));
+    }
+
+    /**
+     * 휴가 부여 삭제
+     * DELETE /v1/leaves/grants/{id}
+     */
+    public function destroyGrant(int $id): JsonResponse
+    {
+        return ApiResponse::handle(function () use ($id) {
+            return $this->service->destroyGrant($id);
+        }, __('message.deleted'));
+    }
 }