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/services/usage.ts

@@ -1,12 +1,12 @@
-import request from './request'
+import request, { withSignal } from './request'
 import type { UsageRecord, UsageByModel } from '@/types'
 
 export const usageService = {
-  daily: (params?: { days?: number }) =>
-    request.get<{ by_day: UsageRecord[] }>('/usage', { params: { ...params, group_by: 'day' } })
+  daily: (params?: { days?: number }, signal?: AbortSignal) =>
+    request.get<{ by_day: UsageRecord[] }>('/usage', withSignal({ params: { ...params, group_by: 'day' } }, signal))
       .then((r) => r.data.by_day || []),
 
-  byModel: (params?: { days?: number }) =>
-    request.get<{ by_model: UsageByModel[] }>('/usage', { params: { ...params, group_by: 'model' } })
+  byModel: (params?: { days?: number }, signal?: AbortSignal) =>
+    request.get<{ by_model: UsageByModel[] }>('/usage', withSignal({ params: { ...params, group_by: 'model' } }, signal))
       .then((r) => r.data.by_model || []),
 }