Adds QR code scanning functionality to both ServerSetupActivity and
SettingsActivity, allowing users to auto-fill server configuration by
scanning a QR code from the server's admin dashboard.
Changes:
- Add ZXing Android Embedded library (v4.3.0) for QR scanning
- Add CAMERA permission to AndroidManifest
- Create QrServerConfig model to parse and validate QR JSON data
- Create QrScannerUtil for shared scanning functionality
- Extend PermissionUtil with camera permission handling
- Add "Scan QR Code" button to ServerSetupActivity with hint text
- Add "Scan QR Code" button to SettingsActivity
- Add QR scan icon and string resources
- Configure Gradle Java toolchain auto-detection
The QR code contains JSON with server address, port, and client key
which are automatically populated into the input fields when scanned.
