refactor: 消除 es-toolkit/compat 依赖，isArray/isObject 替换为原生实现

src/server/checker/runner/http/execute.ts

@@ -1,5 +1,4 @@
 import { isError } from "es-toolkit";
-import { isObject } from "es-toolkit/compat";
 
 import type { CheckResult, RawTargetConfig } from "../../types";
 import type { CheckerContext, CheckerDefinition, CheckerValidationInput, ResolveContext } from "../types";
@@ -161,7 +160,10 @@ function buildRedirectInit(init: RequestInit, statusCode: number, fromUrl: strin
   const method = init.method?.toUpperCase();
 
   if (statusCode === 303 || ((statusCode === 301 || statusCode === 302) && method === "POST")) {
-    const headers = isObject(init.headers) ? { ...(init.headers as Record<string, string>) } : undefined;
+    const headers =
+      typeof init.headers === "object" && init.headers !== null
+        ? { ...(init.headers as Record<string, string>) }
+        : undefined;
     if (headers) {
       for (const key of Object.keys(headers)) {
         const lower = key.toLowerCase();
@@ -176,7 +178,7 @@ function buildRedirectInit(init: RequestInit, statusCode: number, fromUrl: strin
   try {
     const fromOrigin = new URL(fromUrl).origin;
     const toOrigin = new URL(toUrl).origin;
-    if (fromOrigin !== toOrigin && isObject(newInit.headers)) {
+    if (fromOrigin !== toOrigin && typeof newInit.headers === "object" && newInit.headers !== null) {
       const headers = { ...(newInit.headers as Record<string, string>) };
       for (const key of Object.keys(headers)) {
         if (SENSITIVE_HEADERS.has(key.toLowerCase())) {