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/app_bar.dart

@@ -0,0 +1,55 @@
+import 'package:flutter/material.dart';
+
+/// Consistent AppBar builder for TracPulse screens.
+///
+/// Reads base styles (backgroundColor, elevation) from the current
+/// [ThemeData.appBarTheme], then applies TracPulse's standard back button
+/// and title styling on top.
+///
+/// Parameters:
+/// - [title] – App bar title text (left-aligned, monospace, 14px, weight 700, letter-spacing 2)
+/// - [actions] – optional list of action [IconButton]s placed on the right
+/// - [onTitleTap] – optional callback when the title is tapped (e.g. Easter egg)
+AppBar buildTracPulseAppBar({
+  required String title,
+  List<Widget>? actions,
+  VoidCallback? onTitleTap,
+}) {
+  return AppBar(
+    // Inherit backgroundColor, elevation from theme (defined once in MaterialApp.appBarTheme)
+    automaticallyImplyLeading: true,
+    actions: actions,
+    title: onTitleTap != null
+        ? GestureDetector(
+            onTap: onTitleTap,
+            child: Text(
+              title,
+              style: const TextStyle(
+                fontFamily: 'monospace',
+                fontSize: 14,
+                fontWeight: FontWeight.w700,
+                letterSpacing: 2,
+                color: Color(0xFFe0e0e0),
+              ),
+            ),
+          )
+        : Text(
+            title,
+            style: const TextStyle(
+              fontFamily: 'monospace',
+              fontSize: 14,
+              fontWeight: FontWeight.w700,
+              letterSpacing: 2,
+              color: Color(0xFFe0e0e0),
+            ),
+          ),
+    // Consistent back button: #9e9e9e, size 20 (distinct from title #e0e0e0)
+    leading: Builder(
+      builder: (context) => IconButton(
+        icon: const Icon(Icons.arrow_back, color: Color(0xFF9e9e9e), size: 20),
+        onPressed: () => Navigator.pop(context),
+      ),
+    ),
+    leadingWidth: 48,
+  );
+}