fix(ci): correct network matrix generation for workflow dispatch

- Fix JSON array generation for manually triggered deployments
- Ensure a valid JSON array is created when a single network is selected
- Improve matrix configuration for workflow dispatch events

.github/workflows/cd-deploy-nodes-gcp.yml

@@ -240,7 +240,8 @@ jobs:
       - id: set-networks
         run: |
           if [ "${{ github.event_name }}" = "workflow_dispatch" ]; then
-            echo "matrix=[${{ toJSON(inputs.network) }}]" >> $GITHUB_OUTPUT
+            # Manually triggered deployment: output a valid JSON array with the single chosen network.
+            echo "matrix=[\"${{ inputs.network }}\"]" >> $GITHUB_OUTPUT
           else
             echo 'matrix=["Mainnet","Testnet"]' >> $GITHUB_OUTPUT
           fi