Parashell 1.0.1

feat(installer): Add Dropsite automatic updates to Windows installer

- Add ParashellUpdater.ps1 PowerShell script to handle background BITS downloads and verification
- Implement secure update flow with Authenticode signature verification and SHA-256 validation
- Add update check configuration to NSIS declarations for version-aware update logic
- Update installer language strings to support update notifications and prompts
- Modify bundle creation script to include updater in Windows installer package
- Improve README documentation with formatting and new section on secure background updates
- Store updater controller in administrator-protected directory under %ProgramData%\Parashell\Updater
- Enable resumable downloads with global mutex to prevent concurrent transfer conflicts