refactor: extract consistent AppBar builder, remove icon from EVENT LOG title

- 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

lib/info_screen.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/material.dart';
 
+import 'app_bar.dart';
+
 class InfoScreen extends StatelessWidget {
   const InfoScreen({super.key});
 
@@ -7,32 +9,7 @@ class InfoScreen extends StatelessWidget {
   Widget build(BuildContext context) {
     return Scaffold(
       backgroundColor: const Color(0xFF0d0d0d),
-      appBar: AppBar(
-        backgroundColor: const Color(0xFF161616),
-        elevation: 0,
-        leading: IconButton(
-          icon: const Icon(
-            Icons.arrow_back,
-            color: Color(0xFF9e9e9e),
-            size: 20,
-          ),
-          onPressed: () => Navigator.pop(context),
-        ),
-        title: const Text(
-          'HOW IT WORKS',
-          style: TextStyle(
-            fontFamily: 'monospace',
-            fontSize: 14,
-            fontWeight: FontWeight.w700,
-            letterSpacing: 2,
-            color: Color(0xFFe0e0e0),
-          ),
-        ),
-        bottom: PreferredSize(
-          preferredSize: const Size.fromHeight(1),
-          child: Container(height: 1, color: const Color(0xFF2a2a2a)),
-        ),
-      ),
+      appBar: buildTracPulseAppBar(title: 'HOW IT WORKS'),
       body: ListView(
         padding: const EdgeInsets.all(20),
         children: [