fix: 壁纸下内容区统一磨砂背景（可读性修复，浅深色自适应）

db.js

@@ -186,6 +186,7 @@ function seedDefaults() {
     smtp_from_name: 'RainWeb',
     theme_wallpaper: '',
     theme_wallpaper_scale: 'cover',
+    theme_wallpaper_enabled: '1',
     nav_style: 'default',
     card_style: 'default',
     glass_blur: '20',

frontend/src/admin/pages/ThemeSettings.jsx

@@ -19,6 +19,7 @@ export default function ThemeSettings() {
     primary_color: '#6750a4',
     theme_wallpaper: '',
     theme_wallpaper_scale: 'cover',
+    theme_wallpaper_enabled: true,
     nav_style: 'default',
     card_style: 'default',
     glass_blur: '20',
@@ -34,6 +35,7 @@ export default function ThemeSettings() {
         primary_color: s.primary_color || '#6750a4',
         theme_wallpaper: s.theme_wallpaper || '',
         theme_wallpaper_scale: s.theme_wallpaper_scale || 'cover',
+        theme_wallpaper_enabled: s.theme_wallpaper_enabled !== '0',
         nav_style: s.nav_style || 'default',
         card_style: s.card_style || 'default',
         glass_blur: s.glass_blur || '20',
@@ -65,6 +67,7 @@ export default function ThemeSettings() {
         primary_color: form.primary_color,
         theme_wallpaper: form.theme_wallpaper.trim(),
         theme_wallpaper_scale: form.theme_wallpaper_scale,
+        theme_wallpaper_enabled: form.theme_wallpaper_enabled ? '1' : '0',
         theme_force_dark: form.theme_force_dark ? '1' : '0',
         nav_style: form.nav_style,
         card_style: form.card_style,
@@ -92,6 +95,11 @@ export default function ThemeSettings() {
 
       <Paper sx={{ p: 3, mb: 2 }}>
         <Typography variant="subtitle1" sx={{ mb: 1 }}>壁纸背景</Typography>
+        <FormControlLabel
+          control={<Switch checked={form.theme_wallpaper_enabled} onChange={(e) => setForm((p) => ({ ...p, theme_wallpaper_enabled: e.target.checked }))} />}
+          label="启用壁纸背景"
+          sx={{ mb: 1 }}
+        />
         <Box sx={{ display: 'flex', gap: 1, alignItems: 'center', mb: 1 }}>
           <Button variant="outlined" onClick={() => fileRef.current && fileRef.current.click()}>上传图片</Button>
           <input ref={fileRef} type="file" accept="image/*" style={{ display: 'none' }} onChange={handleWallpaperUpload} />

frontend/src/components/Layout.jsx

@@ -76,7 +76,7 @@ export default function Layout() {
     const wallpaper = settings.theme_wallpaper || '';
     const scale = settings.theme_wallpaper_scale || 'cover';
 
-    if (wallpaper) {
+    if (wallpaper && settings.theme_wallpaper_enabled !== '0') {
       body.classList.add('has-wallpaper');
       body.style.setProperty('--wallpaper', `url(${wallpaper})`);
       const bgSizeMap = { cover: 'cover', contain: 'contain', repeat: 'auto', stretch: '100% 100%' };

public/css/style.css

@@ -1559,6 +1559,18 @@ button.glass-card, .btn.glass-card, .nav-tab.glass-card, .chip.glass-card {
   -webkit-backdrop-filter: blur(8px);
 }
 
+/* 壁纸下内容区统一磨砂背景：半透明底 + 模糊，保证文字清晰同时保留壁纸美感 */
+body.has-wallpaper .page {
+  background: rgba(255,251,254,0.65);
+  backdrop-filter: blur(12px);
+  -webkit-backdrop-filter: blur(12px);
+  border-radius: 16px;
+}
+
+[data-theme="dark"] body.has-wallpaper .page {
+  background: rgba(28,27,31,0.6);
+}
+
 /* Forum sidebar glass with wallpaper */
 .has-wallpaper .forum-sidebar .forum-cat-item {
   backdrop-filter: blur(4px);

routes/settings.js

@@ -6,7 +6,7 @@ const router = express.Router();
 
 const PUBLIC_KEYS = ['site_name','site_description','site_url','primary_color',
   'recaptcha_site_key','turnstile_site_key',
-  'theme_wallpaper','theme_wallpaper_scale','nav_style','card_style',
+  'theme_wallpaper','theme_wallpaper_scale','theme_wallpaper_enabled','nav_style','card_style',
   'glass_blur','glass_opacity','theme_force_dark',
   'captcha_type','captcha_login','captcha_register','captcha_forum',
   'homepage_avatar','homepage_bio','homepage_content','blog_show_sidebar',
@@ -15,7 +15,7 @@ const PUBLIC_KEYS = ['site_name','site_description','site_url','primary_color',
 
 const ALL_KEYS = ['site_name','site_description','site_url','primary_color','recaptcha_site_key','turnstile_site_key',
   'smtp_host','smtp_port','smtp_user','smtp_from_email','smtp_from_name',
-  'theme_wallpaper','theme_wallpaper_scale','nav_style','card_style','glass_blur','glass_opacity','theme_force_dark',
+  'theme_wallpaper','theme_wallpaper_scale','theme_wallpaper_enabled','nav_style','card_style','glass_blur','glass_opacity','theme_force_dark',
   'captcha_type','captcha_login','captcha_register','captcha_forum',
   'homepage_avatar','homepage_bio','homepage_content','blog_show_sidebar',
   'site_favicon','homepage_contacts','music_embed_enabled','music_embed_code','music_embed_position','music_embed_autohide','music_embed_idle_timeout',