feat(gpu-service): allow re-typing stopped instances on edit

- Add instance-type column to edit drawer for stopped instances
- Extract saveInstanceDataInDescription into shared util
- Floor sliced unit resources; keep CPU >= 1 core
- Expose applyInstanceType for both create and edit flows

src/pages/gpu-service/instances/utils/instance-description.ts

@@ -0,0 +1,18 @@
+import _ from 'lodash';
+import { InstanceTypeItem } from '../config/types';
+
+// Serialize the chosen instance type into the instance's `description` field —
+// a persisted spec snapshot the form reads back to render the type card and
+// derive unit resources. Shared by the create/recreate flow (card selection)
+// and the edit flow (change-type overlay).
+export const saveInstanceDataInDescription = (
+  instanceType: InstanceTypeItem
+): string => {
+  return JSON.stringify({
+    name: instanceType.name,
+    spec: {
+      ..._.omit(instanceType.spec, ['cache', 'cpu']),
+      cpu: _.pick(instanceType.spec?.cpu, ['manufacturer', 'product', 'family'])
+    }
+  });
+};