[BUG] Missing spec: Microsoft.App/ContainerApps 2026-03-02-preview

### API Spec link

https://github.com/Azure/azure-rest-api-specs/tree/main/specification/app/resource-manager/Microsoft.App/ContainerApps/preview

### API Spec version

2026-03-02-preview

### Describe the bug

The API spec for Microsoft.App/ContainerApps 2026-03-02-preview is missing: https://github.com/Azure/azure-rest-api-specs/tree/main/specification/app/resource-manager/Microsoft.App/ContainerApps/preview

However it's being mentioned in MS Learn doc: https://github.com/MicrosoftDocs/azure-docs/blob/main/articles/container-apps/functions-scale-rule-override.md

As a result dowstream tooling such as AzAPI Terraform is unable to use this API version: https://github.com/Azure/terraform-provider-azapi/issues/1135

### Expected behavior

The spec exists

### Actual behavior

Spec does not exist

### Reproduction Steps

n/a

### Environment

_No response_

Start in specification/app/resource-manager/Microsoft.App/ContainerApps/preview and compare nearby API versions with the Microsoft Learn reference for the 2026-03-02-preview version. Confirm the required resource definitions and conventions before adding the missing specification, then verify that the spec is present and usable by downstream tooling such as AzAPI Terraform.

Written by the indexing model from the issue text.