UI: Add project selection in Create Kubernetes Cluster form (projectid supported by createKubernetesCluster API)

### The required feature described as a wish

ISSUE TYPE
* Improvement Request

COMPONENT NAME
~~~
UI, Kubernetes Service (CKS)
~~~

CLOUDSTACK VERSION
~~~
4.22.1.0
~~~

SUMMARY

The createKubernetesCluster API in 4.22.1.0 supports the `projectid` parameter
("Deploy cluster for the project"), and the API response includes `project` and
`projectid` fields:
https://cloudstack.apache.org/api/apidocs-4.22/apis/createKubernetesCluster.html

However, the "Add Kubernetes Cluster" form in the UI has no field to select a
project. Currently, deploying a CKS cluster into a project can only be
achieved either by calling the API directly (passing projectid), or by
switching the UI view to the specific project before creating the cluster.

There is no way to choose the target project directly from the cluster
creation form itself, unlike other resource creation flows in the UI. This is
inconsistent and inconvenient, especially for admins managing multiple
projects.

STEPS TO REPRODUCE
~~~
1. Log in to the CloudStack 4.22.1 UI Default View
2. Navigate to Compute > Kubernetes > Create Kubernetes Cluster
3. Observe there is no field/dropdown to select a project for the cluster
4. Compare with the createKubernetesCluster API, which accepts "projectid"
~~~

EXPECTED RESULTS
~~~
The "Add Kubernetes Cluster" form should include a project dropdown
(populated via listProjects), so the cluster and its resources are created
under the selected project — equivalent to passing projectid to the
createKubernetesCluster API.
~~~

從 CloudStack UI 中的 Add Kubernetes Cluster 表單開始，查看 createKubernetesCluster API 文件，尤其關注 projectid 以及其回應中的專案欄位。追蹤其他 UI 表單如何使用 listProjects 填入專案。完成的標準是：表單提供專案下拉選單，並在建立叢集時傳遞所選的 projectid。

由索引模型根據 Issue 內容生成。