- Fix set_root_password.sh to update both build-time and live system preseed files
- Update auto-installer.sh to handle crypted passwords from preseed
- Fix cleanup.sh to reset both preseed files to default state
- Add changelog entry documenting the critical bug fix
- Resolve login issue where installed systems always used default password

This fixes the core issue where set_root_password.sh only modified the build-time
preseed file, but the auto-installer used the live system preseed file which
remained unchanged, causing installed systems to always have 'changeme' password.