fix(saas): P1 审计修复 — 连接池断路器 + Worker重试 + XSS防护 + 状态机SQL解析器

P1 修复内容:
- F7: health handler 连接池容量检查 (80%阈值返回503 degraded)
- F9: SSE spawned task 并发限制 (Semaphore 16 permits)
- F10: Key Pool 单次 JOIN 查询优化 (消除 N+1)
- F12: CORS panic → 配置错误
- F14: 连接池使用率计算修正 (ratio = used*100/total)
- F15: SQL 迁移解析器替换为状态机 (支持 $$, DO $body$, 存储过程)
- Worker 重试机制: 失败任务通过 mpsc channel 重新入队
- DOMPurify XSS 防护 (PipelineResultPreview)
- Admin V2: ErrorBoundary + SWR全局配置 + 请求优化

admin-v2/src/pages/Dashboard.tsx

@@ -42,12 +42,12 @@ const actionColors: Record<string, string> = {
 export default function Dashboard() {
   const { data: stats, isLoading: statsLoading, error: statsError } = useQuery({
     queryKey: ['dashboard-stats'],
-    queryFn: () => statsService.dashboard(),
+    queryFn: ({ signal }) => statsService.dashboard(signal),
   })
 
   const { data: logsData, isLoading: logsLoading } = useQuery({
     queryKey: ['recent-logs'],
-    queryFn: () => logService.list({ page: 1, page_size: 10 }),
+    queryFn: ({ signal }) => logService.list({ page: 1, page_size: 10 }, signal),
   })
 
   if (statsError) {