chore: add .env.example for local release script

Author: Prot10

.env.example

@@ -0,0 +1,10 @@
+# Apple Developer Credentials for Notarization
+APPLE_ID=your-apple-id@email.com
+APPLE_APP_SPECIFIC_PASSWORD=xxxx-xxxx-xxxx-xxxx
+APPLE_TEAM_ID=XXXXXXXXXX
+
+# Certificate name (from Keychain Access)
+MACOS_CERTIFICATE_NAME=Developer ID Application: Your Name (XXXXXXXXXX)
+
+# Sparkle EdDSA private key (base64)
+SPARKLE_PRIVATE_KEY=your-sparkle-private-key-here