- Added settings UI to enable/disable .bak file creation when saving files
- Created settings storage in .obsidian/obsiviewer.json to persist backup preferences
- Added API endpoints to read/write backup settings (/api/settings)
- Implemented automatic cleanup of existing .bak files when disabling backups
- Modified file save operations to respect backup setting across notes, bookmarks and graph files
- Removed existing .bak files from version control
