fix: 크롤링 중복 URL 제거 + URL 정규화 강화

- normalize_url: www. prefix 제거, UTM 등 트래킹 파라미터 제거
- site inspection: 크롤링 후 검사 전 중복 URL 필터링
- batch inspection: 업로드 URL 목록 중복 제거

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

backend/app/services/site_inspection_service.py

@@ -302,9 +302,13 @@ class SiteInspectionService:
             if not discovered:
                 raise ValueError("크롤링 결과가 없습니다. URL을 확인해주세요.")
 
-            # Build discovered_pages documents
+            # Build discovered_pages documents (중복 URL 제거)
             discovered_pages = []
+            seen_urls: set[str] = set()
             for page in discovered:
+                if page["url"] in seen_urls:
+                    continue
+                seen_urls.add(page["url"])
                 discovered_pages.append({
                     "url": page["url"],
                     "depth": page["depth"],
@@ -444,14 +448,6 @@ class SiteInspectionService:
         """Run inspection for a single discovered page."""
         inspection_id = str(uuid.uuid4())
 
-        # Publish page_start event
-        await self._publish_site_event(site_inspection_id, {
-            "event_type": "page_start",
-            "site_inspection_id": site_inspection_id,
-            "page_url": page_url,
-            "page_index": page_index,
-        })
-
         # Mark page as inspecting in MongoDB
         await self.db.site_inspections.update_one(
             {