System Logs:
- Add scroll_offset tracking with auto-scroll to bottom on new logs
- Up/Down/j/k keys to scroll line by line
- PageUp/PageDown for page scrolling
- Home/End to jump to top/bottom
- Show scroll indicators in title: [^v], [SCROLL] when not auto-scrolling
- Display log count in title
Editor:
- Fix scroll_offset to follow cursor when moving up/down
- Add PageUp/PageDown for faster navigation
- Add Ctrl+Home/Ctrl+End to jump to start/end of file
- ensure_cursor_visible() keeps cursor in view
Tab Navigation:
- FileTree -> Editor (if open) or Logs -> Chat -> back to start
- Consistent cycling through all panels
