feat(gpu-service): scope create forms by the selected organization

In the platform-admin "all organizations" view, add an organization picker
(the CreateOrgScopeField slot) to the SSH public key, storage type,
storage, GPU instance and instance-template create forms, placed below the
name / display-name fields. Drop the hidden owner field and let the owner
derive from the request context, matching the model-route form.

For GPU instances, scope the instance-type list to clusters the chosen org
owns (client-side, by cluster owner) so an instance can't be scheduled onto
another org's cluster; when the org owns none, show "no instance type
available" and clear the selection, cluster and CPU/memory fields. Instance
templates gain a Global level (NULL owner) and an owner tag on the card.

src/pages/_components/owner-principal-id-field.tsx

@@ -1,36 +0,0 @@
-import { currentOrganizationIdAtom } from '@/atoms/user';
-import { Input as CInput } from '@gpustack/core-ui';
-import { Form } from 'antd';
-import type { NamePath } from 'antd/es/form/interface';
-import { useAtomValue } from 'jotai';
-import { useEffect } from 'react';
-
-interface OwnerPrincipalIdFieldProps {
-  name?: NamePath;
-}
-
-// Pins `owner_principal_id` to the Org the caller is currently acting
-// under. Cluster ownership is irrelevant here: cluster_access grants
-// let one Org schedule on another Org's cluster, but the resource the
-// caller creates still belongs to *their* Org, and the backend enforces
-// `owner_principal_id == ctx.current_principal_id`.
-const OwnerPrincipalIdField: React.FC<OwnerPrincipalIdFieldProps> = ({
-  name = 'owner_principal_id'
-}) => {
-  const currentOrgId = useAtomValue(currentOrganizationIdAtom);
-  const form = Form.useFormInstance();
-
-  useEffect(() => {
-    if (currentOrgId != null) {
-      form.setFieldValue(name, currentOrgId);
-    }
-  }, [currentOrgId, name, form]);
-
-  return (
-    <Form.Item name={name} hidden>
-      <CInput.Input />
-    </Form.Item>
-  );
-};
-
-export default OwnerPrincipalIdField;