优化编号讲解布局与返回流程

- 将讲解编号置于标题上方并增强辨识度
- 编号详情返回后保留输入界面并清空原编号
- 增加页面栈丢失时恢复编号输入页的兜底逻辑
- 补充编号布局和返回流程回归测试

Made-with: Proma

tests/unit/ExhibitDetailAudioFirst.spec.ts

@@ -465,6 +465,40 @@ describe('讲解详情音频优先布局', () => {
     expect(mocks.toggleMute).not.toHaveBeenCalled()
   })
 
+  it('编号入口详情返回时回到原编号输入页', async () => {
+    vi.stubGlobal('getCurrentPages', vi.fn(() => [
+      { route: 'pages/explain/list', options: {} },
+      { route: 'pages/exhibit/detail', options: { entry: 'code' } }
+    ]))
+    const wrapper = mount(ExhibitDetail, {
+      global: { stubs: { GuidePageFrame: GuidePageFrameStub } }
+    })
+    await mocks.onLoadHandler?.({ id: exhibit.id, stopId: 'stop-1', entry: 'code' })
+    await flushPromises()
+
+    wrapper.getComponent(GuidePageFrameStub).vm.$emit('back')
+    await flushPromises()
+
+    expect(uni.navigateBack).toHaveBeenCalledWith(expect.objectContaining({ delta: 1 }))
+    expect(uni.redirectTo).not.toHaveBeenCalled()
+  })
+
+  it('编号入口详情丢失页面栈时回退到自动打开的编号输入页', async () => {
+    const wrapper = mount(ExhibitDetail, {
+      global: { stubs: { GuidePageFrame: GuidePageFrameStub } }
+    })
+    await mocks.onLoadHandler?.({ id: exhibit.id, stopId: 'stop-1', entry: 'code' })
+    await flushPromises()
+
+    wrapper.getComponent(GuidePageFrameStub).vm.$emit('back')
+    await flushPromises()
+
+    expect(uni.navigateBack).not.toHaveBeenCalled()
+    expect(uni.redirectTo).toHaveBeenCalledWith(expect.objectContaining({
+      url: '/pages/explain/list?codeEntry=1'
+    }))
+  })
+
   it('上一页是讲解对象列表时使用页面栈返回', async () => {
     vi.stubGlobal('getCurrentPages', vi.fn(() => [
       { route: 'pages/explain/guide-stop-list', options: {} },