- Upgrade Microsoft.WindowsAppSDK from 1.6 to 1.8 (latest stable)
- Add WindowsAppSdkDeploymentType=SelfContained to bundle the WinUI
  runtime with the app — no external runtime installation required
- Remove runtime bootstrapper download step from CI workflow
- Remove runtime installer from Inno Setup script

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>