Fix antiforgery token errors by restoring autoConfigureDataProtection in Azure Container Apps (#804)

### Summary & Motivation

Upgrade the Azure Container Apps API version from `2025-07-01` (stable)
to `2025-10-02-preview` to restore the `autoConfigureDataProtection`
runtime setting for .NET containers.

When upgrading to the stable `2025-07-01` API version in PR #793, the
`autoConfigureDataProtection` feature was inadvertently lost because it
remains a preview-only feature not included in stable releases. This
change reverts to a preview API version that supports this feature,
which enables automatic configuration of ASP.NET Data Protection keys
across all container apps in an environment - essential for antiforgery
token validation when multiple container apps (AppGateway,
account-management, back-office, etc.) need to share encrypted tokens.

The learning here is that stable API versions may not include all
preview features that the infrastructure depends on. When upgrading API
versions, verify that preview features are still available or
consciously choose to remain on a preview version until the required
features become stable.

### Checklist

- [x] I have added tests, or done manual regression tests
- [x] I have updated the documentation, if necessary

Author: tjementum

cloud-infrastructure/modules/container-app.bicep

@@ -60,7 +60,7 @@ var image = useQuickStartImage
 // Create a revisionSuffix that contains the version and random suffix. E.g. "2025-11-19-756-a3f2"
 var fullRevisionSuffix = '${replace(containerImageTag, '.', '-')}-${revisionSuffix}'
 
-resource containerApp 'Microsoft.App/containerApps@2025-07-01' = {
+resource containerApp 'Microsoft.App/containerApps@2025-10-02-preview' = {
   name: name
   location: location
   tags: tags
@@ -149,6 +149,11 @@ resource containerApp 'Microsoft.App/containerApps@2025-07-01' = {
           identity: userAssignedIdentity.id
         }
       ]
+      runtime: {
+        dotnet: {
+          autoConfigureDataProtection: true
+        }
+      }
       ingress: ingress
         ? {
             external: external