fix(h5): 统一 nh=1 与 sbh 顶距逻辑，与 index.html 首屏一致

applyMpEmbedDom 在原生顶栏模式读取 session sbh；补充 nh+sbh 单测。

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/user-h5/src/lib/mpEmbed.spec.ts

@@ -4,6 +4,9 @@ import { applyMpEmbedDom, initMpEmbed, isMpEmbed, isMpNativeHeader } from './mpE
 describe('mpEmbed', () => {
   beforeEach(() => {
     sessionStorage.clear()
+    document.documentElement.className = ''
+    document.documentElement.style.removeProperty('--yxg-safe-top')
+    document.documentElement.style.removeProperty('--yxg-page-top')
     window.history.replaceState({}, '', '/psy/')
   })
 
@@ -37,6 +40,17 @@ describe('mpEmbed', () => {
     expect(document.documentElement.style.getPropertyValue('--yxg-page-top')).toBe('4px')
   })
 
+  it('applies sbh in native header mode with ?nh=1&sbh=', () => {
+    window.history.replaceState({}, '', '/psy/?mp=1&nh=1&sbh=12')
+    initMpEmbed()
+    expect(isMpNativeHeader()).toBe(true)
+    expect(sessionStorage.getItem('yxg_sbh')).toBe('12')
+    expect(document.documentElement.style.getPropertyValue('--yxg-page-top')).toBe('12px')
+    window.history.replaceState({}, '', '/psy/?mp=1&nh=1')
+    applyMpEmbedDom()
+    expect(document.documentElement.style.getPropertyValue('--yxg-page-top')).toBe('12px')
+  })
+
   it('returns false without mp query', () => {
     initMpEmbed()
     expect(isMpEmbed()).toBe(false)