feat: implement gallery logo customization (Issue #17)

Added comprehensive logo customization features for gallery views:
- Logo size options (small, medium, large, xlarge, custom)
- Logo position control (left, center, right)
- Display mode settings (logo only, text only, logo and text)
- Visibility controls for header and hero sections
- Custom height configuration for fine-tuning

Changes:
- Added database migration for 6 new logo customization settings
- Extended backend APIs to handle logo customization fields
- Updated GalleryLayout.tsx with dynamic logo rendering logic
- Added logo upload functionality to BrandingPage.tsx
- Extended settings service with logo customization types

This addresses the issue where the gallery logo was "very large and centered"
by providing full control over logo appearance and positioning.

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

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

backend/migrations/041_add_logo_customization_settings.js

@@ -0,0 +1,89 @@
+exports.up = async function(knex) {
+  console.log('Running migration: 041_add_logo_customization_settings');
+  
+  // Add default logo customization settings
+  const logoSettings = [
+    {
+      setting_key: 'branding_logo_size',
+      setting_value: JSON.stringify('medium'),
+      setting_type: 'branding',
+      description: 'Logo size: small, medium, large, xlarge, or custom',
+      created_at: new Date(),
+      updated_at: new Date()
+    },
+    {
+      setting_key: 'branding_logo_max_height',
+      setting_value: JSON.stringify(48),
+      setting_type: 'branding', 
+      description: 'Maximum logo height in pixels (used when size is custom)',
+      created_at: new Date(),
+      updated_at: new Date()
+    },
+    {
+      setting_key: 'branding_logo_position',
+      setting_value: JSON.stringify('left'),
+      setting_type: 'branding',
+      description: 'Logo position in header: left, center, right',
+      created_at: new Date(),
+      updated_at: new Date()
+    },
+    {
+      setting_key: 'branding_logo_display_header',
+      setting_value: JSON.stringify(true),
+      setting_type: 'branding',
+      description: 'Show logo in gallery header',
+      created_at: new Date(),
+      updated_at: new Date()
+    },
+    {
+      setting_key: 'branding_logo_display_hero',
+      setting_value: JSON.stringify(true),
+      setting_type: 'branding',
+      description: 'Show logo in hero section (for non-grid layouts)',
+      created_at: new Date(),
+      updated_at: new Date()
+    },
+    {
+      setting_key: 'branding_logo_display_mode',
+      setting_value: JSON.stringify('logo_and_text'),
+      setting_type: 'branding',
+      description: 'Display mode: logo_only, text_only, logo_and_text',
+      created_at: new Date(),
+      updated_at: new Date()
+    }
+  ];
+
+  // Insert settings that don't already exist
+  for (const setting of logoSettings) {
+    const exists = await knex('app_settings')
+      .where('setting_key', setting.setting_key)
+      .first();
+    
+    if (!exists) {
+      await knex('app_settings').insert(setting);
+      console.log(`Added setting: ${setting.setting_key}`);
+    } else {
+      console.log(`Setting already exists: ${setting.setting_key}`);
+    }
+  }
+
+  console.log('Migration 041_add_logo_customization_settings completed');
+};
+
+exports.down = async function(knex) {
+  console.log('Rolling back migration: 041_add_logo_customization_settings');
+  
+  // Remove the logo customization settings
+  await knex('app_settings')
+    .whereIn('setting_key', [
+      'branding_logo_size',
+      'branding_logo_max_height',
+      'branding_logo_position',
+      'branding_logo_display_header',
+      'branding_logo_display_hero',
+      'branding_logo_display_mode'
+    ])
+    .del();
+  
+  console.log('Rollback of 041_add_logo_customization_settings completed');
+};

backend/src/routes/adminSettings.js

@@ -170,7 +170,13 @@ router.put('/branding', adminAuth, async (req, res) => {
       watermark_size,
       favicon_url,
       logo_url,
-      watermark_logo_url
+      watermark_logo_url,
+      logo_size,
+      logo_max_height,
+      logo_position,
+      logo_display_header,
+      logo_display_hero,
+      logo_display_mode
     } = req.body;
 
     const brandingSettings = {
@@ -184,7 +190,13 @@ router.put('/branding', adminAuth, async (req, res) => {
       watermark_size,
       favicon_url,
       logo_url,
-      watermark_logo_url
+      watermark_logo_url,
+      logo_size,
+      logo_max_height,
+      logo_position,
+      logo_display_header,
+      logo_display_hero,
+      logo_display_mode
     };
 
     // Handle favicon deletion if empty string or null is provided

backend/src/routes/publicSettings.js

@@ -42,6 +42,12 @@ router.get('/', async (req, res) => {
       branding_watermark_size: settingsObject.branding_watermark_size || 15,
       branding_favicon_url: settingsObject.branding_favicon_url || '',
       branding_logo_url: settingsObject.branding_logo_url || '',
+      branding_logo_size: settingsObject.branding_logo_size || 'medium',
+      branding_logo_max_height: settingsObject.branding_logo_max_height || 48,
+      branding_logo_position: settingsObject.branding_logo_position || 'left',
+      branding_logo_display_header: settingsObject.branding_logo_display_header !== false,
+      branding_logo_display_hero: settingsObject.branding_logo_display_hero !== false,
+      branding_logo_display_mode: settingsObject.branding_logo_display_mode || 'logo_and_text',
       theme_config: settingsObject.theme_config || null,
       default_language: settingsObject.general_default_language || 'en',
       enable_analytics: settingsObject.general_enable_analytics !== false,