feat: 三层明暗模式 + 移动端代码块适配

- 新增 useTheme.js 单例主题管理器：用户手动选择 > 系统偏好 > 时间自动切换(8AM/6PM)
- config.ts 添加 head 内联脚本防止主题闪烁
- 移动端导航按钮右对齐(margin-left:auto)
- 首页和文档页代码块移动端溢出修复

.vitepress/config.ts

@@ -63,6 +63,18 @@ export default defineConfig({
     ['link', { rel: 'icon', href: '/favicon.png' }],
     ['meta', { property: 'og:image', content: '/og-image.png' }],
     ['meta', { name: 'theme-color', content: '#C8963E' }],
+    ['script', {}, `
+      (function(){
+        var E='mengstack-theme-explicit',V='vitepress-theme-appearance';
+        var d=false,e=localStorage.getItem(E);
+        if(e!==null){d=e==='true'}
+        else if(window.matchMedia&&window.matchMedia('(prefers-color-scheme:dark)').matches){d=true}
+        else if(window.matchMedia&&window.matchMedia('(prefers-color-scheme:light)').matches){d=false}
+        else{var h=new Date().getHours();d=h<8||h>=18}
+        if(d)document.documentElement.classList.add('dark');
+        try{localStorage.setItem(V,String(d))}catch(x){}
+      })()
+    `],
   ],
 
   transformHead({ pageData }) {

.vitepress/theme/Home.vue

@@ -18,7 +18,7 @@
           <a href="/community">社区</a>
         </nav>
         <div class="home-nav-actions">
-          <button class="home-icon-btn" aria-label="切换明暗主题" title="切换主题" @click="toggleDark">
+          <button class="home-icon-btn" aria-label="切换明暗主题" title="切换主题" @click="handleToggle">
             <svg aria-hidden="true" class="sun" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round"><circle cx="12" cy="12" r="4"/><path d="M12 2v2m0 16v2M4.9 4.9l1.4 1.4m11.4 11.4 1.4 1.4M2 12h2m16 0h2M4.9 19.1l1.4-1.4M17.7 6.3l1.4-1.4"/></svg>
             <svg aria-hidden="true" class="moon" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M21 12.8A9 9 0 1 1 11.2 3 7 7 0 0 0 21 12.8z"/></svg>
           </button>
@@ -338,18 +338,14 @@ Check /health</pre>
 
 <script setup>
 import { ref, onMounted, onUnmounted, watch } from 'vue'
-import { useData } from 'vitepress'
+import { initThemeManager } from './useTheme'
 
-const { isDark } = useData()
+const { isDark, handleToggle } = initThemeManager()
 
 const navEl = ref(null)
 const scrollY = ref(0)
 const menuOpen = ref(false)
 
-function toggleDark() {
-  isDark.value = !isDark.value
-}
-
 function copyCode(e) {
   const btn = e.currentTarget
   const pre = btn.parentElement.querySelector('pre')
@@ -780,6 +776,7 @@ watch(menuOpen, (open) => {
   .home-stat{padding:10px 0}
   .home-nav-links{display:none}
   .hamburger{display:grid}
+  .home-nav-actions{margin-left:auto}
   .home-nav.nav-menu-open .home-nav-links{
     display:flex;flex-direction:column;position:absolute;top:64px;left:0;right:0;
     background:var(--home-bg);border-bottom:1px solid var(--home-border);padding:12px 20px 18px;gap:2px;
@@ -799,7 +796,10 @@ watch(menuOpen, (open) => {
   .home-stats-grid{grid-template-columns:1fr}
   .home-trust-inner{gap:10px 16px}
   .home-chip{font-size:13px;padding:5px 10px}
-  .home-terminal-body{font-size:12.5px;padding:16px}
+  .home-terminal-body{font-size:12px;padding:14px 12px;-webkit-overflow-scrolling:touch}
+  .home-terminal{border-radius:10px}
+  .home-codeblock{padding:12px 14px;border-radius:8px;-webkit-overflow-scrolling:touch}
+  .home-codeblock pre{font-size:11.5px;line-height:1.6}
   .home-hero h1{font-size:clamp(28px,7vw,38px)}
   .home-about .home-about-card{padding:24px 18px}
   .home-cta-card{padding:40px 20px}
@@ -814,6 +814,8 @@ watch(menuOpen, (open) => {
   .home-brand img{width:26px;height:26px}
   .home-badge{font-size:12px;padding:5px 10px}
   .home-hero{padding:100px 0 48px}
+  .home-terminal-body{font-size:11px;padding:12px 10px}
+  .home-codeblock pre{font-size:11px}
 }
 @media (prefers-reduced-motion:reduce){
   .home-root *,.home-root *::before,.home-root *::after{animation-duration:.01ms!important;transition-duration:.01ms!important;scroll-behavior:auto!important}

.vitepress/theme/Layout.vue

@@ -3,6 +3,9 @@ import DefaultTheme from 'vitepress/theme'
 import { useRoute } from 'vitepress'
 import { computed, watch, onMounted, onUnmounted } from 'vue'
 import Home from './Home.vue'
+import { initThemeManager } from './useTheme'
+
+initThemeManager()
 
 const route = useRoute()
 const isHome = computed(() => route.path === '/' || route.path === '/index.html')

.vitepress/theme/custom.css

@@ -633,6 +633,28 @@
   .vp-doc .content-container {
     padding: 0 16px !important;
   }
+
+  /* Code blocks mobile */
+  .vp-doc div[class*='language-'] {
+    margin: 12px 0 !important;
+    border-radius: 8px !important;
+  }
+  .vp-doc div[class*='language-'] pre {
+    font-size: 12.5px !important;
+    -webkit-overflow-scrolling: touch;
+  }
+  .vp-doc pre {
+    overflow-x: auto;
+    -webkit-overflow-scrolling: touch;
+    border-radius: 8px;
+    font-size: 12.5px;
+    line-height: 1.6;
+  }
+  .vp-doc pre code {
+    white-space: pre;
+    word-break: keep-all;
+    overflow-wrap: normal;
+  }
 }
 
 /* --- Small mobile <420 --- */
@@ -644,6 +666,13 @@
     padding: 0 20px !important;
     font-size: 0.88rem !important;
   }
+  .vp-doc div[class*='language-'] pre {
+    font-size: 11.5px !important;
+  }
+  .vp-doc pre {
+    font-size: 11.5px;
+    border-radius: 6px;
+  }
 }
 
 /* ============ HOME LAYOUT OVERRIDES ============ */

.vitepress/theme/useTheme.js

@@ -0,0 +1,125 @@
+import { onMounted, onUnmounted } from 'vue'
+import { useData } from 'vitepress'
+
+const EXPLICIT_KEY = 'mengstack-theme-explicit'
+const VP_KEY = 'vitepress-theme-appearance'
+const DAY_START = 8
+const NIGHT_START = 18
+
+let initialized = false
+let _isDark = null
+let _handleToggle = null
+
+function isTimeDark() {
+  const h = new Date().getHours()
+  return h < DAY_START || h >= NIGHT_START
+}
+
+function getSystemPref() {
+  if (typeof window === 'undefined' || !window.matchMedia) return null
+  if (window.matchMedia('(prefers-color-scheme: dark)').matches) return true
+  if (window.matchMedia('(prefers-color-scheme: light)').matches) return false
+  return null
+}
+
+export function initThemeManager() {
+  if (initialized) return { isDark: _isDark, handleToggle: _handleToggle }
+
+  const vp = useData()
+  const isDark = vp.isDark
+  initialized = true
+  _isDark = isDark
+
+  let explicitChoice = null
+  let timer = null
+  let sysListener = null
+  let observer = null
+  let suppressObs = false
+
+  function sync(value) {
+    suppressObs = true
+    isDark.value = value
+    try {
+      localStorage.setItem(VP_KEY, String(value))
+      document.documentElement.classList.toggle('dark', value)
+    } catch {}
+    setTimeout(() => { suppressObs = false }, 150)
+  }
+
+  function doAutoSwitch() {
+    const shouldBeDark = isTimeDark()
+    if (isDark.value !== shouldBeDark) {
+      sync(shouldBeDark)
+    }
+  }
+
+  function handleToggle() {
+    explicitChoice = !isDark.value
+    try { localStorage.setItem(EXPLICIT_KEY, String(explicitChoice)) } catch {}
+    if (timer) { clearInterval(timer); timer = null }
+    sync(explicitChoice)
+  }
+
+  _handleToggle = handleToggle
+
+  onMounted(() => {
+    try {
+      const stored = localStorage.getItem(EXPLICIT_KEY)
+      if (stored !== null) explicitChoice = stored === 'true'
+    } catch {}
+
+    if (explicitChoice !== null) {
+      sync(explicitChoice)
+    } else {
+      const sysPref = getSystemPref()
+      if (sysPref !== null) {
+        sync(sysPref)
+      } else {
+        sync(isTimeDark())
+      }
+    }
+
+    timer = setInterval(() => {
+      if (explicitChoice !== null) return
+      if (getSystemPref() !== null) return
+      doAutoSwitch()
+    }, 30000)
+
+    if (typeof window !== 'undefined' && window.matchMedia) {
+      const mql = window.matchMedia('(prefers-color-scheme: dark)')
+      sysListener = (e) => {
+        if (explicitChoice !== null) return
+        sync(e.matches)
+      }
+      mql.addEventListener('change', sysListener)
+    }
+
+    if (typeof document !== 'undefined') {
+      observer = new MutationObserver(() => {
+        if (suppressObs) return
+        const dark = document.documentElement.classList.contains('dark')
+        if (explicitChoice === null) {
+          explicitChoice = dark
+          try { localStorage.setItem(EXPLICIT_KEY, String(explicitChoice)) } catch {}
+        }
+        isDark.value = dark
+        try { localStorage.setItem(VP_KEY, String(dark)) } catch {}
+      })
+      observer.observe(document.documentElement, {
+        attributes: true,
+        attributeFilter: ['class']
+      })
+    }
+  })
+
+  onUnmounted(() => {
+    if (timer) clearInterval(timer)
+    if (sysListener && typeof window !== 'undefined' && window.matchMedia) {
+      window.matchMedia('(prefers-color-scheme: dark)').removeEventListener('change', sysListener)
+    }
+    if (observer) observer.disconnect()
+    initialized = false
+  })
+
+  return { isDark, handleToggle }
+}