feat: 优化步骤 5 提交逻辑，点击后立即上报完成状态，避免等待页面结果

tests/background-step5-submit-short-circuit.test.js

@@ -0,0 +1,52 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+
+const source = fs.readFileSync('background/steps/fill-profile.js', 'utf8');
+const globalScope = {};
+const api = new Function('self', `${source}; return self.MultiPageBackgroundStep5;`)(globalScope);
+
+test('step 5 transport error returns immediately after completion signal arrives', async () => {
+  const events = {
+    redirectWaitCalls: 0,
+    onboardingCalls: 0,
+    logs: [],
+  };
+
+  const transportError = new Error('The message port closed before a response was received.');
+
+  const executor = api.createStep5Executor({
+    addLog: async (message, level) => {
+      events.logs.push({ message, level: level || 'info' });
+    },
+    generateRandomBirthday: () => ({ year: 2003, month: 6, day: 19 }),
+    generateRandomName: () => ({ firstName: 'Test', lastName: 'User' }),
+    getState: async () => ({
+      stepStatuses: {
+        5: 'completed',
+      },
+    }),
+    getTabId: async () => 123,
+    handleChatgptOnboardingSkip: async () => {
+      events.onboardingCalls += 1;
+    },
+    isRetryableContentScriptTransportError: (error) => error === transportError,
+    LOG_PREFIX: '[test]',
+    sendToContentScript: async () => {
+      throw transportError;
+    },
+    waitForStep5ChatgptRedirect: async () => {
+      events.redirectWaitCalls += 1;
+      return { id: 123, url: 'https://chatgpt.com/' };
+    },
+  });
+
+  await executor.executeStep5();
+
+  assert.equal(events.redirectWaitCalls, 0, '收到完成信号后不应再等待 ChatGPT 跳转');
+  assert.equal(events.onboardingCalls, 0, '收到完成信号后不应再触发 onboarding 跳过');
+  assert.ok(
+    events.logs.some(({ message }) => /已收到完成信号，直接结束当前步骤/.test(message)),
+    '应记录 Step 5 已按完成信号直接结束'
+  );
+});