Fix brand theme application and add comprehensive translations

- Fixed theme not being reflected on gallery and admin login pages
- Created GlobalThemeProvider to apply themes globally
- Updated gallery and admin login pages to use dynamic CSS variables
- Added complete translations for all admin sections in English and German:
  - Notifications management
  - Event view and creation
  - Photo upload functionality
  - Category management
  - Archive page view
  - Analytics dashboard
  - Branding and theme settings
  - System settings
  - CMS page management
  - Email configuration
- Fixed admin photo management display issues
- Fixed photo upload category assignment
- Added password reset functionality for galleries
- Improved error handling and user feedback

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

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

backend/scripts/test-upload.js

@@ -0,0 +1,59 @@
+const axios = require('axios');
+const FormData = require('form-data');
+const fs = require('fs');
+const path = require('path');
+
+async function testUpload() {
+  try {
+    // First login
+    console.log('1. Logging in as admin...');
+    const loginResponse = await axios.post('http://localhost:3000/api/admin/auth/login', {
+      username: 'admin',
+      password: 'admin123'
+    });
+    
+    const token = loginResponse.data.token;
+    console.log('✓ Login successful');
+    
+    // Create a test image file
+    const testImagePath = path.join(__dirname, 'test-image.png');
+    const imageBuffer = Buffer.from('iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNkYPhfDwAChwGA60e6kgAAAABJRU5ErkJggg==', 'base64');
+    fs.writeFileSync(testImagePath, imageBuffer);
+    
+    // Test upload
+    console.log('\n2. Testing upload with category_id=7...');
+    const form = new FormData();
+    form.append('photos', fs.createReadStream(testImagePath), 'test-image.png');
+    form.append('category_id', '7');
+    
+    console.log('Form data headers:', form.getHeaders());
+    
+    try {
+      const uploadResponse = await axios.post(
+        'http://localhost:3000/api/admin/events/12/upload',
+        form,
+        {
+          headers: {
+            ...form.getHeaders(),
+            'Authorization': `Bearer ${token}`
+          }
+        }
+      );
+      
+      console.log('✓ Upload successful:', uploadResponse.data);
+    } catch (error) {
+      console.error('✗ Upload failed:', error.response?.status, error.response?.data);
+      if (error.response?.data) {
+        console.error('Error details:', JSON.stringify(error.response.data, null, 2));
+      }
+    }
+    
+    // Clean up
+    fs.unlinkSync(testImagePath);
+    
+  } catch (error) {
+    console.error('Error:', error.message);
+  }
+}
+
+testUpload();