feat: 사이트 검사 동시 검사 수 설정 추가

- 기본값 2→4로 변경, 사용자가 [1, 2, 4, 8] 중 선택 가능
- 백엔드: concurrency 파라미터 추가 (API → 서비스 → Semaphore)
- 프론트: 드롭다운에 "동시 검사 수" 옵션 UI 추가

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/inspection/UrlInputForm.tsx

@@ -18,6 +18,9 @@ const MAX_PAGES_OPTIONS = [10, 20, 50, 0] as const;
 /** 크롤링 깊이 옵션 */
 const MAX_DEPTH_OPTIONS = [1, 2, 3] as const;
 
+/** 동시 검사 수 옵션 */
+const CONCURRENCY_OPTIONS = [1, 2, 4, 8] as const;
+
 export function UrlInputForm() {
   const [url, setUrl] = useState("");
   const [error, setError] = useState<string | null>(null);
@@ -26,6 +29,7 @@ export function UrlInputForm() {
   const [showSiteOptions, setShowSiteOptions] = useState(false);
   const [maxPages, setMaxPages] = useState<number>(20);
   const [maxDepth, setMaxDepth] = useState<number>(2);
+  const [concurrency, setConcurrency] = useState<number>(4);
   const router = useRouter();
   const { setInspection } = useInspectionStore();
   const { setSiteInspection } = useSiteInspectionStore();
@@ -101,7 +105,8 @@ export function UrlInputForm() {
       const response = await api.startSiteInspection(
         trimmedUrl,
         maxPages,
-        maxDepth
+        maxDepth,
+        concurrency
       );
       setSiteInspection(response.site_inspection_id, trimmedUrl);
       router.push(
@@ -225,7 +230,7 @@ export function UrlInputForm() {
                     </div>
 
                     {/* 크롤링 깊이 */}
-                    <div className="mb-4">
+                    <div className="mb-3">
                       <label className="text-xs text-muted-foreground mb-1.5 block">
                         크롤링 깊이
                       </label>
@@ -250,6 +255,32 @@ export function UrlInputForm() {
                       </div>
                     </div>
 
+                    {/* 동시 검사 수 */}
+                    <div className="mb-4">
+                      <label className="text-xs text-muted-foreground mb-1.5 block">
+                        동시 검사 수
+                      </label>
+                      <div className="flex gap-2">
+                        {CONCURRENCY_OPTIONS.map((option) => (
+                          <Button
+                            key={option}
+                            type="button"
+                            variant={
+                              concurrency === option ? "default" : "outline"
+                            }
+                            size="sm"
+                            className={cn(
+                              "flex-1",
+                              concurrency === option && "pointer-events-none"
+                            )}
+                            onClick={() => setConcurrency(option)}
+                          >
+                            {option}
+                          </Button>
+                        ))}
+                      </div>
+                    </div>
+
                     {/* 사이트 검사 시작 버튼 */}
                     <Button
                       type="button"

frontend/src/lib/api.ts

@@ -157,7 +157,8 @@ class ApiClient {
   async startSiteInspection(
     url: string,
     maxPages?: number,
-    maxDepth?: number
+    maxDepth?: number,
+    concurrency?: number
   ): Promise<StartSiteInspectionResponse> {
     return this.request("/api/site-inspections", {
       method: "POST",
@@ -165,6 +166,7 @@ class ApiClient {
         url,
         max_pages: maxPages,
         max_depth: maxDepth,
+        concurrency: concurrency,
       }),
     });
   }