refactor: HTTP checker 质量加固

- failure actual 截断格式改为 …(共 N 字符)，标量不序列化直接返回
- 新增 redos.ts 实现 ReDoS 静态检测（嵌套量词/重叠交替），启动期拒绝危险正则
- JSON body rules 共享同一次 JSON.parse 结果，避免重复解析
- checkCssRule 重构为线性流程，消除 exist:true 与无 operator 的冗余分支
- extract checkEarlyTimeout 辅助函数，明确提前 duration 检查意图
- 补充 303/307/308 重定向、相对路径 Location、混合 body rules 集成测试

tests/server/checker/runner/shared/failure.test.ts

@@ -12,18 +12,18 @@ describe("truncateActual", () => {
     expect(truncateActual(str)).toBe(str);
   });
 
-  test("超过限制长度截断并加省略号", () => {
+  test("超过限制长度截断并加省略号与字符计数", () => {
     const str = "a".repeat(300);
     const result = truncateActual(str) as string;
-    expect(result.length).toBe(203);
-    expect(result.endsWith("...")).toBe(true);
+    expect(result).toBe(`${"a".repeat(200)}…(共 300 字符)`);
+    expect(result.includes("...")).toBe(false);
     expect(result.startsWith("a".repeat(200))).toBe(true);
   });
 
   test("自定义最大长度", () => {
     const str = "abcdefghij";
     const result = truncateActual(str, 5) as string;
-    expect(result).toBe("abcde...");
+    expect(result).toBe("abcde…(共 10 字符)");
   });
 
   test("null 不截断", () => {
@@ -34,9 +34,16 @@ describe("truncateActual", () => {
     expect(truncateActual(undefined)).toBe(undefined);
   });
 
-  test("数字转换为字符串后判断", () => {
+  test("标量不截断", () => {
     expect(truncateActual(42)).toBe(42);
-    expect(truncateActual(123456789, 3) as string).toBe("123...");
+    expect(truncateActual(123456789, 3)).toBe(123456789);
+    expect(truncateActual(true, 3)).toBe(true);
+  });
+
+  test("对象序列化后超限时截断", () => {
+    const result = truncateActual({ value: "x".repeat(20) }, 10) as string;
+    expect(result.startsWith('{"value":"')).toBe(true);
+    expect(result.endsWith("…(共 32 字符)")).toBe(true);
   });
 });
 
@@ -56,8 +63,7 @@ describe("mismatchFailure", () => {
   test("自动截断过长的 actual", () => {
     const longStr = "x".repeat(300);
     const f = mismatchFailure("body", "body[0]", "short", longStr, "too long");
-    expect((f.actual as string).endsWith("...")).toBe(true);
-    expect((f.actual as string).length).toBe(203);
+    expect(f.actual).toBe(`${"x".repeat(200)}…(共 300 字符)`);
   });
 });