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/step6.js

@@ -0,0 +1,93 @@
+(function attachBackgroundStep6(root, factory) {
+  root.MultiPageBackgroundStep6 = factory();
+})(typeof self !== 'undefined' ? self : globalThis, function createBackgroundStep6Module() {
+  function createStep6Executor(deps = {}) {
+    const {
+      addLog,
+      completeStepFromBackground,
+      getLoginAuthStateLabel,
+      getState,
+      isStep6RecoverableResult,
+      isStep6SuccessResult,
+      refreshOAuthUrlBeforeStep6,
+      reuseOrCreateTab,
+      runPreStep6CookieCleanup,
+      sendToContentScriptResilient,
+      shouldSkipLoginVerificationForCpaCallback,
+      skipLoginVerificationStepsForCpaCallback,
+      throwIfStopped,
+    } = deps;
+
+    async function executeStep6(state) {
+      if (shouldSkipLoginVerificationForCpaCallback(state)) {
+        await skipLoginVerificationStepsForCpaCallback();
+        return;
+      }
+      if (!state.email) {
+        throw new Error('缺少邮箱地址，请先完成步骤 3。');
+      }
+
+      await runPreStep6CookieCleanup();
+
+      let attempt = 0;
+
+      while (true) {
+        throwIfStopped();
+        attempt += 1;
+        const currentState = attempt === 1 ? state : await getState();
+        const password = currentState.password || currentState.customPassword || '';
+        const oauthUrl = await refreshOAuthUrlBeforeStep6(currentState);
+
+        if (attempt === 1) {
+          await addLog('步骤 6：正在打开最新 OAuth 链接并登录...');
+        } else {
+          await addLog(`步骤 6：上一轮登录未进入验证码页，正在重新发起第 ${attempt} 轮登录尝试...`, 'warn');
+        }
+
+        await reuseOrCreateTab('signup-page', oauthUrl);
+
+        const result = await sendToContentScriptResilient(
+          'signup-page',
+          {
+            type: 'EXECUTE_STEP',
+            step: 6,
+            source: 'background',
+            payload: {
+              email: currentState.email,
+              password,
+            },
+          },
+          {
+            timeoutMs: 180000,
+            retryDelayMs: 700,
+            logMessage: '步骤 6：认证页正在切换，等待页面重新就绪后继续登录...',
+          }
+        );
+
+        if (result?.error) {
+          throw new Error(result.error);
+        }
+
+        if (isStep6SuccessResult(result)) {
+          await completeStepFromBackground(6, {
+            loginVerificationRequestedAt: result.loginVerificationRequestedAt || null,
+          });
+          return;
+        }
+
+        if (isStep6RecoverableResult(result)) {
+          const reasonMessage = result.message
+            || `当前停留在${getLoginAuthStateLabel(result.state)}，准备重新执行步骤 6。`;
+          await addLog(`步骤 6：${reasonMessage}`, 'warn');
+          continue;
+        }
+
+        throw new Error('步骤 6：认证页未返回可识别的登录结果。');
+      }
+    }
+
+    return { executeStep6 };
+  }
+
+  return { createStep6Executor };
+});