feat: 접근성 검사 표준 선택 기능 — WCAG/KWCAG 버전별 선택 지원

3가지 검사 모드(한 페이지, 사이트 크롤링, 목록 업로드) 모두에서 접근성 표준을
선택할 수 있도록 추가. WCAG 2.0 A/AA, 2.1 AA, 2.2 AA와 KWCAG 2.1, 2.2를
지원하며, KWCAG 선택 시 axe-core 결과를 KWCAG 검사항목으로 자동 매핑.

- KWCAG 2.2 (33항목) / 2.1 (24항목) ↔ WCAG 매핑 테이블 (kwcag_mapping.py)
- AccessibilityChecker에 표준 파싱 및 KWCAG 변환 로직 추가
- 전체 API 파이프라인에 accessibility_standard 파라미터 전파
- 프론트엔드 3개 폼에 공용 표준 선택 드롭다운 추가

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

backend/app/services/site_inspection_service.py

@@ -50,6 +50,7 @@ class SiteInspectionService:
         max_pages: int = 20,
         max_depth: int = 2,
         concurrency: int = 4,
+        accessibility_standard: str = "wcag_2.1_aa",
     ) -> str:
         """
         Start a site-wide inspection.
@@ -84,6 +85,7 @@ class SiteInspectionService:
                 "max_pages": max_pages,
                 "max_depth": max_depth,
                 "concurrency": concurrency,
+                "accessibility_standard": accessibility_standard,
             },
             "discovered_pages": [],
             "aggregate_scores": None,
@@ -91,13 +93,16 @@ class SiteInspectionService:
         await self.db.site_inspections.insert_one(doc)
 
         logger.info(
-            "Site inspection started: id=%s, url=%s, max_pages=%d, max_depth=%d, concurrency=%d",
-            site_inspection_id, url, max_pages, max_depth, concurrency,
+            "Site inspection started: id=%s, url=%s, max_pages=%d, max_depth=%d, concurrency=%d, standard=%s",
+            site_inspection_id, url, max_pages, max_depth, concurrency, accessibility_standard,
         )
 
         # Launch background task
         asyncio.create_task(
-            self._crawl_and_inspect(site_inspection_id, url, max_pages, max_depth, concurrency)
+            self._crawl_and_inspect(
+                site_inspection_id, url, max_pages, max_depth, concurrency,
+                accessibility_standard=accessibility_standard,
+            )
         )
 
         return site_inspection_id
@@ -272,6 +277,7 @@ class SiteInspectionService:
         max_pages: int,
         max_depth: int,
         concurrency: int = 4,
+        accessibility_standard: str = "wcag_2.1_aa",
     ) -> None:
         """
         Background task that runs in two phases:
@@ -366,6 +372,7 @@ class SiteInspectionService:
                     page_url=page["url"],
                     page_index=idx,
                     total_pages=len(discovered_pages),
+                    accessibility_standard=accessibility_standard,
                 )
                 for idx, page in enumerate(discovered_pages)
             ]
@@ -428,6 +435,7 @@ class SiteInspectionService:
         page_url: str,
         page_index: int,
         total_pages: int,
+        accessibility_standard: str = "wcag_2.1_aa",
     ) -> None:
         """Inspect a single page with semaphore-controlled concurrency."""
         async with semaphore:
@@ -436,6 +444,7 @@ class SiteInspectionService:
                 page_url=page_url,
                 page_index=page_index,
                 total_pages=total_pages,
+                accessibility_standard=accessibility_standard,
             )
 
     async def _inspect_single_page(
@@ -444,6 +453,7 @@ class SiteInspectionService:
         page_url: str,
         page_index: int,
         total_pages: int,
+        accessibility_standard: str = "wcag_2.1_aa",
     ) -> None:
         """Run inspection for a single discovered page."""
         inspection_id = str(uuid.uuid4())
@@ -480,6 +490,7 @@ class SiteInspectionService:
                 url=page_url,
                 inspection_id=inspection_id,
                 progress_callback=page_progress_callback,
+                accessibility_standard=accessibility_standard,
             )
 
             overall_score = result.get("overall_score", 0)