Enable hard delete option for event theme deletion

Updated the delete mutation to include a `hard_delete` query parameter. This ensures themes are permanently removed when deleted. The change improves clarity and control over deletion behavior.

frontend/src/context/event-theme-context.tsx

@@ -137,9 +137,10 @@ export const EventThemesProvider: React.FC<EventThemesProviderProps> = ({
 
   const deleteMutation = useMutation({
     mutationFn: (id: string) =>
-      deleteEventTheme({ path: { theme_id: id } }).then(
-        (result) => result.data,
-      ),
+      deleteEventTheme({
+        path: { theme_id: id },
+        query: { hard_delete: true },
+      }).then((result) => result.data),
     onSuccess: () =>
       queryClient.invalidateQueries({
         queryKey: listEventThemesOptions().queryKey,