0.2.0-macos: Add file viewer, syntax highlighting, port monitor, and rail resizing
- New file viewer panel in SFTP workspace with preview/edit/log modes - Syntax highlighting via syntect for code files (15+ languages) - Listening port monitor via ss -tlnp/ulnp sampling - Draggable resource rail left edge resizing - File viewer: search, replace, pagination, save-back-to-server - Improved SFTP error handling and connection robustness