优化黑暗模式和白天模式

public/js/app.js

@@ -183,6 +183,17 @@
 
     // Auth & Theme listeners
     dom.themeToggle.addEventListener('change', toggleTheme);
+    
+    // System Theme Listener (Real-time)
+    const systemThemeMedia = window.matchMedia('(prefers-color-scheme: light)');
+    if (systemThemeMedia.addEventListener) {
+      systemThemeMedia.addEventListener('change', () => {
+        const savedTheme = localStorage.getItem('theme') || (window.SITE_SETTINGS && window.SITE_SETTINGS.default_theme) || 'dark';
+        if (savedTheme === 'auto') {
+          applyTheme('auto');
+        }
+      });
+    }
     dom.btnLogin.addEventListener('click', openLoginModal);
     dom.closeLoginModal.addEventListener('click', closeLoginModal);
     dom.loginForm.addEventListener('submit', handleLogin);
@@ -1705,6 +1716,16 @@
         networkChart.draw();
       }
     }
+
+    // Default Theme
+    if (settings.default_theme) {
+      if (dom.defaultThemeInput) dom.defaultThemeInput.value = settings.default_theme;
+      // If setting is 'auto', we also sync immediately
+      const savedTheme = localStorage.getItem('theme');
+      if (!savedTheme || savedTheme === 'auto') {
+        applyTheme(settings.default_theme);
+      }
+    }
   }
 
   async function saveSiteSettings() {
@@ -1723,6 +1744,11 @@
       p95_type: dom.p95TypeSelect.value
     };
 
+    // If user sets default to auto, we should clear their manual override or set it to auto
+    if (settings.default_theme === 'auto') {
+      localStorage.setItem('theme', 'auto');
+    }
+
     dom.btnSaveSiteSettings.disabled = true;
     dom.btnSaveSiteSettings.textContent = '保存中...';