Add read-only admin functionality and enhance billing models in admin interface

backend/igny8_core/business/integration/admin.py

@@ -0,0 +1,36 @@
+from django.contrib import admin
+from igny8_core.admin.base import AccountAdminMixin
+from .models import SiteIntegration, SyncEvent
+
+
+@admin.register(SiteIntegration)
+class SiteIntegrationAdmin(AccountAdminMixin, admin.ModelAdmin):
+    list_display = [
+        'site',
+        'platform',
+        'platform_type',
+        'is_active',
+        'sync_enabled',
+        'sync_status',
+        'last_sync_at',
+    ]
+    list_filter = ['platform', 'platform_type', 'is_active', 'sync_enabled', 'sync_status']
+    search_fields = ['site__name', 'site__domain', 'platform']
+    readonly_fields = ['created_at', 'updated_at']
+
+
+@admin.register(SyncEvent)
+class SyncEventAdmin(AccountAdminMixin, admin.ModelAdmin):
+    list_display = [
+        'integration',
+        'site',
+        'event_type',
+        'action',
+        'success',
+        'external_id',
+        'created_at',
+    ]
+    list_filter = ['event_type', 'action', 'success', 'created_at']
+    search_fields = ['integration__site__name', 'site__name', 'description', 'external_id']
+    readonly_fields = ['created_at']
+