BU-5: bs-updater technical paper in Simplified Technical English Replace the placeholder Home page with a 14-chapter technical paper that documents bs-updater in full: scope, system description, update sources, installation, configuration, operation, command reference, architecture, distribution notes, verification, release procedure, fault isolation, the ASD-STE100 compliance statement and a glossary. Add _Sidebar.md and _Footer.md for navigation. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>