Add GitHub Actions for automated DMG builds

Features:
- Build DMG for both arm64 (Apple Silicon) and x86_64 (Intel)
- Automatic release creation when tags are pushed
- Multi-architecture support using matrix strategy
- Upload artifacts to GitHub releases

Workflow:
1. Triggered only on tag push (e.g., v1.0.0)
2. Build job: Compiles for arm64 and x86_64 in parallel
3. Release job: Creates GitHub release with both DMGs

Build Scripts Updates:
- Support VERSION environment variable
- Dynamic version in Info.plist
- Dynamic version in DMG filename

Release Artifacts:
- uskey-v{version}-arm64.dmg (Apple Silicon)
- uskey-v{version}-x86_64.dmg (Intel)

Files:
- .github/workflows/release.yml: CI/CD workflow
- build-app.sh: Support VERSION env var
- build-dmg.sh: Support VERSION env var

Usage:

🤖 Generated with [Qoder](https://qoder.com)

build-app.sh

@@ -4,6 +4,7 @@ set -e
 echo "Building uskey.app..."
 
 APP_NAME="uskey"
+VERSION="${VERSION:-1.0.0}"
 BUILD_DIR=".build/release"
 APP_DIR="$BUILD_DIR/$APP_NAME.app"
 CONTENTS_DIR="$APP_DIR/Contents"
@@ -57,7 +58,7 @@ cat > "$CONTENTS_DIR/Info.plist" << EOF
     <key>CFBundlePackageType</key>
     <string>APPL</string>
     <key>CFBundleShortVersionString</key>
-    <string>1.0.0</string>
+    <string>$VERSION</string>
     <key>CFBundleVersion</key>
     <string>1</string>
     <key>LSMinimumSystemVersion</key>