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

backend/igny8_core/business/optimization/admin.py

@@ -0,0 +1,12 @@
+from django.contrib import admin
+from igny8_core.admin.base import AccountAdminMixin
+from .models import OptimizationTask
+
+
+@admin.register(OptimizationTask)
+class OptimizationTaskAdmin(AccountAdminMixin, admin.ModelAdmin):
+    list_display = ['content', 'account', 'status', 'credits_used', 'created_at']
+    list_filter = ['status', 'created_at']
+    search_fields = ['content__title', 'account__name']
+    readonly_fields = ['created_at', 'updated_at']
+