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/src/database/db.js

@@ -161,7 +161,16 @@ async function initializeDatabase() {
       table.json('metadata'); // Additional data about the activity
       table.integer('event_id').references('id').inTable('events');
       table.datetime('created_at').defaultTo(db.fn.now());
+      table.datetime('read_at').nullable();
     });
+  } else {
+    // Check if read_at column exists
+    const hasReadAt = await db.schema.hasColumn('activity_logs', 'read_at');
+    if (!hasReadAt) {
+      await db.schema.table('activity_logs', (table) => {
+        table.datetime('read_at').nullable();
+      });
+    }
   }
 }