Fix Sparkle key generation to create new private key

- Use -f flag to generate new private key file instead of -x flag
- -x flag is for existing keys, -f flag is for new key generation
- Fix 'No existing signing key found!' error in key generation
- Ensure proper new Sparkle key generation in CI/CD pipeline

Author: devopsmariocom

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

@@ -205,8 +205,8 @@ jobs:
           echo "📁 Available Sparkle tools:"
           ls -la ./bin/
           
-          # Use generate_keys tool with correct syntax
-          ./bin/generate_keys -x keys/ed25519_private_key.pem
+          # Generate new private key (no -x flag for new key generation)
+          ./bin/generate_keys -f keys/ed25519_private_key.pem
           
           # Extract public key from private key
           ./bin/generate_keys -x keys/ed25519_private_key.pem -p > keys/ed25519_public_key.pem