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/checker/runner/http/runner.test.ts

@@ -757,7 +757,7 @@ describe("HttpChecker.resolve", () => {
       { http: { url: "https://example.com" }, name: "test", type: "http" },
       makeResolveContext(),
     );
-    expect((result as ResolvedHttpTarget).http.ignoreSSL).toBe(false);
+    expect(result.http.ignoreSSL).toBe(false);
   });
 
   test("maxRedirects 默认值为 0", () => {
@@ -765,7 +765,7 @@ describe("HttpChecker.resolve", () => {
       { http: { url: "https://example.com" }, name: "test", type: "http" },
       makeResolveContext(),
     );
-    expect((result as ResolvedHttpTarget).http.maxRedirects).toBe(0);
+    expect(result.http.maxRedirects).toBe(0);
   });
 
   test("合法 status 范围模式通过校验", () => {
@@ -773,7 +773,7 @@ describe("HttpChecker.resolve", () => {
       { expect: { status: ["2xx", 301] }, http: { url: "https://example.com" }, name: "test", type: "http" },
       makeResolveContext(),
     );
-    expect((result as ResolvedHttpTarget).expect?.status).toEqual(["2xx", 301]);
+    expect(result.expect?.status).toEqual(["2xx", 301]);
   });
 
   test("显式 ignoreSSL 和 maxRedirects 正确解析", () => {
@@ -781,7 +781,7 @@ describe("HttpChecker.resolve", () => {
       { http: { ignoreSSL: true, maxRedirects: 3, url: "https://example.com" }, name: "test", type: "http" },
       makeResolveContext(),
     );
-    expect((result as ResolvedHttpTarget).http.ignoreSSL).toBe(true);
-    expect((result as ResolvedHttpTarget).http.maxRedirects).toBe(3);
+    expect(result.http.ignoreSSL).toBe(true);
+    expect(result.http.maxRedirects).toBe(3);
   });
 });