refactor: 后端架构加固 — 泛型化、批量查询、bootstrap 统一、路径修复与 pageSize 上限

- CheckerDefinition 泛型化，HTTP/Command checker 移除 resolved target 断言
- 新增 ProbeStore.getAllRecentSamples 消除 targets 路由 N+1 查询
- 统一 getAllTargetStats 与 getTargetStats 的 availability 精度
- Engine rejected 结果写入 internal error 记录，提升可观测性
- 新增 bootstrap.ts 统一 dev/production 启动序列
- dataDir 相对路径改为基于配置文件目录解析
- validatePagination 增加 pageSize 上限 200 校验
- 修复 ErrorBoundary override 标记
- 更新 README/DEVELOPMENT 文档，新增完整测试覆盖

tests/server/app.test.ts

@@ -183,6 +183,19 @@ describe("API 路由", () => {
     expect(body.total).toBe(2);
   });
 
+  test("history pageSize 超过上限返回 400", async () => {
+    const targets = store.getTargets();
+    const from = "2024-01-01T00:00:00.000Z";
+    const to = "2026-12-31T23:59:59.999Z";
+    const response = fetchHandler(
+      new Request(`http://localhost/api/targets/${targets[0]!.id}/history?from=${from}&to=${to}&pageSize=201`),
+    );
+    const body = (await response.json()) as Record<string, unknown>;
+
+    expect(response.status).toBe(400);
+    expect(body["error"]).toBe("pageSize must not exceed 200");
+  });
+
   test("/api/targets/:id/trend 返回趋势数据", async () => {
     const targets = store.getTargets();
     const from = "2024-01-01T00:00:00.000Z";