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

crates/zclaw-saas/src/relay/service.rs

@@ -298,7 +298,21 @@ pub async fn execute_relay(
                     let body = axum::body::Body::from_stream(body_stream);
 
                     // SSE 流结束后异步记录 usage + Key 使用量
+                    // 使用全局 Arc<Semaphore> 限制并发 spawned tasks，防止高并发时耗尽连接池
+                    static SSE_SPAWN_SEMAPHORE: std::sync::OnceLock<Arc<tokio::sync::Semaphore>> = std::sync::OnceLock::new();
+                    let semaphore = SSE_SPAWN_SEMAPHORE.get_or_init(|| Arc::new(tokio::sync::Semaphore::new(16)));
+                    let permit = match semaphore.clone().try_acquire_owned() {
+                        Ok(p) => p,
+                        Err(_) => {
+                            // 信号量满时跳过 usage 记录，流本身不受影响
+                            tracing::warn!("SSE usage spawn at capacity, skipping usage record for task {}", task_id);
+                            return Ok(RelayResponse::Sse(body));
+                        }
+                    };
+
                     tokio::spawn(async move {
+                        let _permit = permit; // 持有 permit 直到任务完成
+                        tokio::time::sleep(std::time::Duration::from_secs(3)).await;
                         tokio::time::sleep(std::time::Duration::from_secs(3)).await;
                         let capture = usage_capture.lock().await;
                         let (input, output) = (
@@ -464,11 +478,11 @@ async fn validate_provider_url(url: &str) -> SaasResult<()> {
     // 去除 IPv6 方括号
     let host = host.trim_start_matches('[').trim_end_matches(']');
 
-    // 精确匹配的阻止列表
+    // 精确匹配的阻止列表: 仅包含主机名和特殊域名
+    // 私有 IP 范围 (10.x, 172.16-31.x, 192.168.x, 127.x, 169.254.x, ::1 等)
+    // 由 is_private_ip() 统一判断，无需在此重复列出
     let blocked_exact = [
-        "127.0.0.1", "0.0.0.0", "localhost", "::1", "::ffff:127.0.0.1",
-        "0:0:0:0:0:ffff:7f00:1", "169.254.169.254", "metadata.google.internal",
-        "10.0.0.1", "172.16.0.1", "192.168.0.1",
+        "localhost", "metadata.google.internal",
     ];
     if blocked_exact.contains(&host) {
         return Err(SaasError::InvalidInput(format!("provider URL 指向禁止的内网地址: {}", host)));