fix: sync ROUTE_ORDER with nav order, guard against navigation race condition

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/router.js

@@ -80,12 +80,13 @@ async function importPage(pagePath) {
 // --------------------------------------------------------
 let currentUser = null;
 let currentPath = null;
+let isNavigating = false;
 
 // --------------------------------------------------------
 // Router
 // --------------------------------------------------------
 
-const ROUTE_ORDER = ['/', '/tasks', '/shopping', '/meals', '/calendar',
+const ROUTE_ORDER = ['/', '/tasks', '/calendar', '/meals', '/shopping',
                      '/notes', '/contacts', '/budget', '/settings'];
 
 function getDirection(fromPath, toPath) {
@@ -103,6 +104,10 @@ function getDirection(fromPath, toPath) {
  * @param {boolean} pushState - false beim initialen Load und popstate
  */
 async function navigate(path, userOrPushState = true, pushState = true) {
+  if (isNavigating) return;
+  isNavigating = true;
+
+  try {
     // Überlastung: navigate(path, user) nach Login vs navigate(path, false) beim Init
     if (typeof userOrPushState === 'object' && userOrPushState !== null) {
       currentUser = userOrPushState;
@@ -123,6 +128,7 @@ async function navigate(path, userOrPushState = true, pushState = true) {
         currentUser = result.user;
       } catch {
         currentPath = null; // Reset damit navigate('/login') nicht geblockt wird
+        isNavigating = false;
         navigate('/login');
         return;
       }
@@ -130,6 +136,7 @@ async function navigate(path, userOrPushState = true, pushState = true) {
 
     if (!route.requiresAuth && currentUser && path === '/login') {
       currentPath = null;
+      isNavigating = false;
       navigate('/');
       return;
     }
@@ -141,6 +148,9 @@ async function navigate(path, userOrPushState = true, pushState = true) {
     await renderPage(route, previousPath);
     updateNav(path);
     updateThemeColorForRoute(route);
+  } finally {
+    isNavigating = false;
+  }
 }
 
 /**