fix: 安全性与代码质量加固（异常保护、外键级联、竞态修复、优雅关机）

src/server/checker/engine.ts

@@ -15,7 +15,7 @@ export class ProbeEngine {
   constructor(store: ProbeStore, targets: ResolvedTarget[], maxConcurrentChecks?: number) {
     this.store = store;
     this.targets = targets;
-    this.maxConcurrentChecks = maxConcurrentChecks ?? 10;
+    this.maxConcurrentChecks = maxConcurrentChecks ?? 20;
     this.refreshCache();
   }
 
@@ -86,6 +86,8 @@ export class ProbeEngine {
     for (const result of results) {
       if (result.status === "fulfilled") {
         this.writeResult(result.value);
+      } else {
+        console.warn("探针执行失败:", result.reason);
       }
     }
   }