Fix azure/login: pass creds JSON with client secret

Without client-secret, azure/login assumes OIDC federated auth which
requires id-token write permissions. Use creds JSON format instead.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: johnmathews

.github/workflows/deploy.yml

@@ -23,10 +23,7 @@ jobs:
       - name: Log in to Azure
         uses: azure/login@v2
         with:
-          client-id: ${{ secrets.ACR_CLIENT_ID }}
-          tenant-id: ${{ secrets.AZURE_TENANT_ID }}
-          subscription-id: ${{ secrets.AZURE_SUBSCRIPTION_ID }}
-          enable-AzPSSession: false
+          creds: '{"clientId":"${{ secrets.ACR_CLIENT_ID }}","clientSecret":"${{ secrets.ACR_CLIENT_SECRET }}","tenantId":"${{ secrets.AZURE_TENANT_ID }}","subscriptionId":"${{ secrets.AZURE_SUBSCRIPTION_ID }}"}'
 
       - name: Set AKS context
         run: |