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

Cargo.toml

@@ -110,6 +110,9 @@ argon2 = "0.5"
 totp-rs = "5"
 hex = "0.4"
 
+# TCP socket configuration
+socket2 = { version = "0.5", features = ["all"] }
+
 # Internal crates
 zclaw-types = { path = "crates/zclaw-types" }
 zclaw-memory = { path = "crates/zclaw-memory" }