fix(pro7.5): stabilize icloud/session flow and logged-in step skipping

tests/background-message-router-step2-skip.test.js

@@ -170,6 +170,20 @@ test('message router skips steps 3/4/5 when step 2 detects already logged-in ses
   assert.equal(events.logs[0]?.message, '步骤 2：检测到当前已登录会话，已自动跳过步骤 3/4/5，流程将直接进入步骤 6。');
 });
 
+test('message router skips step 5 when step 4 reports already logged-in transition', async () => {
+  const { router, events } = createRouter({
+    state: { stepStatuses: { 5: 'pending' } },
+  });
+
+  await router.handleStepData(4, {
+    emailTimestamp: 123,
+    skipProfileStep: true,
+  });
+
+  assert.deepStrictEqual(events.stepStatuses, [{ step: 5, status: 'skipped' }]);
+  assert.equal(events.logs[0]?.message, '步骤 4：检测到账号已直接进入已登录态，已自动跳过步骤 5。');
+});
+
 test('message router finalizes step 3 before marking it completed', async () => {
   const { router, events } = createRouter();