Add verification for Sparkle private key generation

- Add check to verify private key file was created successfully
- Add success message for private key generation
- Add error handling if private key generation fails
- Ensure proper key generation workflow in CI/CD pipeline

Author: devopsmariocom

.github/workflows/build-and-release.yml

@@ -205,9 +205,17 @@ jobs:
           echo "📁 Available Sparkle tools:"
           ls -la ./bin/
           
-          # Generate new private key (no -x flag for new key generation)
+          # Generate new private key and save to file
           ./bin/generate_keys -f keys/ed25519_private_key.pem
           
+          # Verify private key was created
+          if [ ! -f "keys/ed25519_private_key.pem" ]; then
+            echo "❌ Failed to generate private key"
+            exit 1
+          fi
+          
+          echo "✅ Private key generated successfully"
+          
           # Extract public key from private key
           ./bin/generate_keys -x keys/ed25519_private_key.pem -p > keys/ed25519_public_key.pem