Add comprehensive group customization features

- Add group overlay color and opacity settings
- Add font customization (body and heading fonts)
- Add group description text color control
- Add option to hide 'Groups' title
- Update frontend DesignSettings interface
- Update CustomizationPanel with new UI controls
- Update Django model with new fields
- Create migration for new customization options
- Update DRF serializer with validation

backend/customization/migrations/0007_designsettings_body_font_family_and_more.py

@@ -0,0 +1,48 @@
+# Generated by Django 5.2.8 on 2025-11-09 01:26
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('customization', '0006_designsettings_cover_overlay_color_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='designsettings',
+            name='body_font_family',
+            field=models.CharField(blank=True, default='', help_text='Шрифт для основного текста', max_length=100),
+        ),
+        migrations.AddField(
+            model_name='designsettings',
+            name='group_description_text_color',
+            field=models.CharField(default='#666666', help_text='Цвет текста описаний групп (hex)', max_length=7),
+        ),
+        migrations.AddField(
+            model_name='designsettings',
+            name='group_overlay_color',
+            field=models.CharField(default='#000000', help_text='Цвет перекрытия групп (hex)', max_length=7),
+        ),
+        migrations.AddField(
+            model_name='designsettings',
+            name='group_overlay_enabled',
+            field=models.BooleanField(default=False, help_text='Включить цветовое перекрытие групп'),
+        ),
+        migrations.AddField(
+            model_name='designsettings',
+            name='group_overlay_opacity',
+            field=models.FloatField(default=0.3, help_text='Прозрачность перекрытия групп (0.0 - 1.0)'),
+        ),
+        migrations.AddField(
+            model_name='designsettings',
+            name='heading_font_family',
+            field=models.CharField(blank=True, default='', help_text='Шрифт для заголовков', max_length=100),
+        ),
+        migrations.AddField(
+            model_name='designsettings',
+            name='show_groups_title',
+            field=models.BooleanField(default=True, help_text='Показывать заголовок "Группы ссылок"'),
+        ),
+    ]