- Add buildTracPulseAppBar() helper in lib/app_bar.dart
- Reads backgroundColor/elevation from ThemeData.appBarTheme
- Consistent back button (#9e9e9e, size 20) via Navigator.pop
- Monospace title style (14px, weight 700, letter-spacing 2)
- Optional onTitleTap for tappable titles
- Update all screens to use the new helper, removing redundant overrides
- Remove terminal icon from status_screen title, use plain centered text
- Change appBarTheme centerTitle to false (left-aligned)
- Remove bottom dividers from all screens
