refactor: 去重器改用 API 并修复 tag 唯一性约束处理

- deduplicator: 从直接数据库查询改为调用 /api/webhook/check-duplicates API
- database-ingestor: 使用 JSON 文件传参避免 curl 编码问题
- webhook: 修复 tag name 唯一性约束冲突，更新时删除旧关联重建
- 添加 check-duplicates API 端点用于批量去重检测
- 适配 ProjectTag 显式关联表的数据查询逻辑
- ProjectCard: 修复 getProjectIcon 空值处理

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/components/project/ProjectCard.tsx

@@ -30,8 +30,10 @@ interface ProjectCardProps {
 }
 
 // Icon mapping for projects based on tags
-function getProjectIcon(tags: Array<{ name: string }>): string {
-  const tagNames = tags.map(t => t.name.toLowerCase())
+function getProjectIcon(tags: Array<{ name: string | null }>): string {
+  const tagNames = tags
+    .map(t => t.name?.toLowerCase())
+    .filter((name): name is string => Boolean(name))
   if (tagNames.some(t => t.includes('automation') || t.includes('workflow'))) return '⚙️'
   if (tagNames.some(t => t.includes('image') || t.includes('art'))) return '🎨'
   if (tagNames.some(t => t.includes('chat') || t.includes('assistant'))) return '💬'