修复无法保存数据的错误

public/js/app.js

@@ -285,43 +285,44 @@
       dom.btnCancelEditRoute.onclick = cancelEditRoute;
     }
 
-    dom.settingsModal.addEventListener('click', (e) => {
-      if (e.target === dom.settingsModal) closeSettings();
-    });
-    dom.btnTest.addEventListener('click', testConnection);
-    dom.btnAdd.addEventListener('click', addSource);
-
     // Auth & Theme listeners
-    dom.themeToggle.addEventListener('change', toggleTheme);
+    if (dom.themeToggle) dom.themeToggle.addEventListener('change', toggleTheme);
+    if (dom.btnSettings) dom.btnSettings.addEventListener('click', openSettings);
+    if (dom.modalClose) dom.modalClose.addEventListener('click', closeSettings);
+    if (dom.btnTest) dom.btnTest.addEventListener('click', testConnection);
+    if (dom.btnAdd) dom.btnAdd.addEventListener('click', addSource);
+    if (dom.btnRefreshNetwork) dom.btnRefreshNetwork.addEventListener('click', fetchNetworkHistory);
 
-    // 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);
+    // Auth & Login
+    if (dom.btnLogin) dom.btnLogin.addEventListener('click', openLoginModal);
+    if (dom.closeLoginModal) dom.closeLoginModal.addEventListener('click', closeLoginModal);
+    if (dom.loginForm) dom.loginForm.addEventListener('submit', handleLogin);
+    if (dom.loginModal) {
       dom.loginModal.addEventListener('click', (e) => {
         if (e.target === dom.loginModal) closeLoginModal();
       });
+    }
 
     // Tab switching
+    if (dom.modalTabs) {
       dom.modalTabs.forEach(tab => {
         tab.addEventListener('click', () => {
           const targetTab = tab.getAttribute('data-tab');
           switchTab(targetTab);
         });
       });
+    }
 
     // Site settings
+    if (dom.btnSaveSiteSettings) {
       dom.btnSaveSiteSettings.addEventListener('click', saveSiteSettings);
+    }
+    if (dom.btnSaveCustomMetrics) {
+      dom.btnSaveCustomMetrics.onclick = saveSiteSettings;
+    }
+    if (dom.btnAddRoute) {
       dom.btnAddRoute.addEventListener('click', addLatencyRoute);
+    }
 
     // Auth password change
     if (dom.btnChangePassword) {