feat: complete remaining Go backend modules

backend/internal/postgres/usage.go

@@ -85,5 +85,8 @@ func (repository UsageRepository) Insert(event usage.Event) (usage.Event, bool,
 func (repository UsageRepository) List(filters usage.Filters) ([]usage.Event, error) {
 	return repository.database.ListUsageEvents(context.Background(), filters)
 }
+func (repository UsageRepository) ListContext(ctx context.Context, filters usage.Filters) ([]usage.Event, error) {
+	return repository.database.ListUsageEvents(ctx, filters)
+}
 
 var _ usage.Repository = UsageRepository{}