- Encrypt sensitive credentials (tokens, passwords) in backup exports using AES-256-GCM with PBKDF2 key derivation from OS username - Backup format v2 with backwards-compatible v1 import - Show dialog to create non-existent directories when changing outputDir, extractDir, or mkvLibraryDir settings Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>