Overview: Removes unused code paths and experimental features that were never part of the FOSS release, leaving a cleaner and more focused codebase.

• Leaner server — doc_search.py reduced by ~300 lines; removed unused network configuration, protocol negotiation, and handler code that had accumulated during development.
• Leaner CLI — docubrowser.py reduced by ~240 lines; removed the setup-tls command and related helpers that are not applicable to a localhost application.
• Stale files removed — deleted branding.json.example and other development-only files that were never used in production.
• Documentation updated — README, INSTALL, and architecture notes cleaned up to accurately reflect the current feature set.