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）

tests/server/checker/store.test.ts

@@ -256,4 +256,45 @@ describe("ProbeStore", () => {
     expect(closedStore.getTargets()).toHaveLength(0);
     expect(closedStore.getTargetById(1)).toBeNull();
   });
+
+  test("删除 target 级联删除 check_results", () => {
+    const cascadeStore = new ProbeStore(join(tempDir, "cascade.db"));
+    const cascadeTarget: ResolvedTarget = {
+      type: "http",
+      name: "cascade-test",
+      group: "default",
+      http: { url: "http://cascade.test", method: "GET", headers: {}, maxBodyBytes: 104857600 },
+      intervalMs: 30000,
+      timeoutMs: 10000,
+    };
+
+    cascadeStore.syncTargets([cascadeTarget]);
+    const t = cascadeStore.getTargets()[0]!;
+
+    cascadeStore.insertCheckResult({
+      targetId: t.id,
+      timestamp: "2025-01-01T00:00:00.000Z",
+      matched: true,
+      durationMs: 100,
+      statusDetail: "200 OK",
+      failure: null,
+    });
+    cascadeStore.insertCheckResult({
+      targetId: t.id,
+      timestamp: "2025-01-01T00:01:00.000Z",
+      matched: false,
+      durationMs: null,
+      statusDetail: null,
+      failure: { kind: "error", phase: "status", path: "$", message: "fail" },
+    });
+
+    expect(cascadeStore.getLatestCheck(t.id)).not.toBeNull();
+
+    cascadeStore.syncTargets([]);
+
+    expect(cascadeStore.getTargets()).toHaveLength(0);
+    expect(cascadeStore.getLatestCheck(t.id)).toBeNull();
+
+    cascadeStore.close();
+  });
 });