feat: implement multi-step background process for user registration

- Add step 1: Open ChatGPT homepage and prepare for signup.
- Add step 2: Handle email submission and ensure the signup entry page is ready.
- Add step 3: Fill in the password using either a custom or generated password.
- Add step 4: Confirm the registration verification page and handle email verification.
- Add step 5: Generate random user details and handle onboarding redirection.
- Add step 6: Manage OAuth login process and handle login verification.
- Add step 7: Retrieve verification code from email and manage retries.
- Add step 8: Handle consent page interactions and manage callback URLs.
- Add step 9: Submit callback information to CPA or SUB2API based on user settings.
- Implement tests to ensure all steps are correctly imported and functional.

background/steps/step1.js

@@ -0,0 +1,21 @@
+(function attachBackgroundStep1(root, factory) {
+  root.MultiPageBackgroundStep1 = factory();
+})(typeof self !== 'undefined' ? self : globalThis, function createBackgroundStep1Module() {
+  function createStep1Executor(deps = {}) {
+    const {
+      addLog,
+      completeStepFromBackground,
+      ensureSignupEntryPageReady,
+    } = deps;
+
+    async function executeStep1() {
+      await addLog('步骤 1：正在打开 ChatGPT 官网...');
+      await ensureSignupEntryPageReady(1);
+      await completeStepFromBackground(1, {});
+    }
+
+    return { executeStep1 };
+  }
+
+  return { createStep1Executor };
+});