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/inspection_service.py

@@ -49,7 +49,11 @@ class InspectionService:
         self.db = db
         self.redis = redis
 
-    async def start_inspection(self, url: str) -> str:
+    async def start_inspection(
+        self,
+        url: str,
+        accessibility_standard: str = "wcag_2.1_aa",
+    ) -> str:
         """
         Start an inspection and return the inspection_id.
         1. Validate URL accessibility (timeout 10s)
@@ -70,7 +74,7 @@ class InspectionService:
 
         # 4. Run inspection as background task
         asyncio.create_task(
-            self._run_inspection(inspection_id, url, response)
+            self._run_inspection(inspection_id, url, response, accessibility_standard)
         )
 
         return inspection_id
@@ -80,6 +84,7 @@ class InspectionService:
         url: str,
         inspection_id: Optional[str] = None,
         progress_callback: Optional[object] = None,
+        accessibility_standard: str = "wcag_2.1_aa",
     ) -> tuple[str, dict]:
         """
         Run a full inspection synchronously (inline) and return the result.
@@ -93,6 +98,7 @@ class InspectionService:
             inspection_id: Optional pre-generated ID. If None, a new UUID is generated.
             progress_callback: Optional async callback(category, progress, current_step).
                                If None, progress is not reported.
+            accessibility_standard: Accessibility standard to use for inspection.
 
         Returns:
             (inspection_id, result_dict) where result_dict is the MongoDB document.
@@ -120,7 +126,10 @@ class InspectionService:
         # Create 4 checker engines
         checkers = [
             HtmlCssChecker(progress_callback=progress_callback),
-            AccessibilityChecker(progress_callback=progress_callback),
+            AccessibilityChecker(
+                progress_callback=progress_callback,
+                standard=accessibility_standard,
+            ),
             SeoChecker(progress_callback=progress_callback),
             PerformanceSecurityChecker(progress_callback=progress_callback),
         ]
@@ -190,6 +199,7 @@ class InspectionService:
             grade=grade,
             categories=categories,
             summary=summary,
+            accessibility_standard=accessibility_standard,
         )
 
         # Store in MongoDB
@@ -203,14 +213,18 @@ class InspectionService:
         await cache_result(inspection_id, doc)
 
         logger.info(
-            "Inspection %s completed (inline): score=%d, duration=%.1fs",
-            inspection_id, overall_score, duration,
+            "Inspection %s completed (inline): score=%d, duration=%.1fs, standard=%s",
+            inspection_id, overall_score, duration, accessibility_standard,
         )
 
         return inspection_id, doc
 
     async def _run_inspection(
-        self, inspection_id: str, url: str, response: httpx.Response
+        self,
+        inspection_id: str,
+        url: str,
+        response: httpx.Response,
+        accessibility_standard: str = "wcag_2.1_aa",
     ) -> None:
         """
         Execute 4 category checks in parallel and store results.
@@ -234,7 +248,10 @@ class InspectionService:
             # Create 4 checker engines
             checkers = [
                 HtmlCssChecker(progress_callback=progress_callback),
-                AccessibilityChecker(progress_callback=progress_callback),
+                AccessibilityChecker(
+                    progress_callback=progress_callback,
+                    standard=accessibility_standard,
+                ),
                 SeoChecker(progress_callback=progress_callback),
                 PerformanceSecurityChecker(progress_callback=progress_callback),
             ]
@@ -322,6 +339,7 @@ class InspectionService:
                 grade=grade,
                 categories=categories,
                 summary=summary,
+                accessibility_standard=accessibility_standard,
             )
 
             # Store in MongoDB
@@ -347,8 +365,8 @@ class InspectionService:
             })
 
             logger.info(
-                "Inspection %s completed: score=%d, duration=%.1fs",
-                inspection_id, overall_score, duration,
+                "Inspection %s completed: score=%d, duration=%.1fs, standard=%s",
+                inspection_id, overall_score, duration, accessibility_standard,
             )
 
         except Exception as e: