Fix language setting not being saved to database on admin settings page

- Added default_language field to general settings state in SettingsPage
- Replaced LanguageSelector component with simple select dropdown on settings page
- Fixed public settings endpoint to read general_default_language from database
- Language setting now properly saved when clicking Save Settings button
- Setting is correctly used by gallery login page and legal pages

🤖 Generated with [Claude Code](https://claude.ai/code)

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

frontend/src/App.tsx

@@ -8,6 +8,8 @@ import { analyticsService } from './services/analytics.service';
 import { GalleryAuthProvider } from './contexts';
 import { ThemeProvider } from './contexts/ThemeContext';
 import { GalleryPage } from './pages/GalleryPage';
+import { PreviewPage } from './pages/gallery/PreviewPage';
+import { LegalPage } from './pages/public/LegalPage';
 import { 
   AdminLoginPage, 
   AdminDashboard, 
@@ -18,10 +20,11 @@ import {
   ArchivesPage,
   AnalyticsPage,
   BrandingPage,
-  SettingsPage
+  SettingsPage,
+  CMSPage
 } from './pages/admin';
 import { AdminLayout, AdminAuthWrapper } from './components/admin';
-import { PageErrorBoundary, OfflineIndicator, SkipLink } from './components/common';
+import { PageErrorBoundary, OfflineIndicator, SkipLink, DynamicFavicon } from './components/common';
 
 // Create a client
 const queryClient = new QueryClient({
@@ -53,10 +56,12 @@ function App() {
     <PageErrorBoundary>
       <QueryClientProvider client={queryClient}>
         <ThemeProvider>
+          <DynamicFavicon />
           <Router>
             <SkipLink />
             <Routes>
               {/* Public gallery routes */}
+              <Route path="/gallery/preview" element={<PreviewPage />} />
               <Route path="/gallery/:slug/:token?" element={
                 <GalleryAuthProvider>
                   <GalleryPage />
@@ -76,10 +81,16 @@ function App() {
                   <Route path="analytics" element={<AnalyticsPage />} />
                   <Route path="branding" element={<BrandingPage />} />
                   <Route path="settings" element={<SettingsPage />} />
+                  <Route path="cms" element={<CMSPage />} />
                   <Route index element={<Navigate to="/admin/dashboard" replace />} />
                 </Route>
               </Route>
 
+              {/* Public legal pages */}
+              <Route path="/impressum" element={<LegalPage />} />
+              <Route path="/datenschutz" element={<LegalPage />} />
+              <Route path="/:slug" element={<LegalPage />} />
+
               {/* Default redirect */}
               <Route path="/" element={<Navigate to="/admin/login" replace />} />
             </Routes>