v1.5.6: UI improvements, logger migration, and bug fixes

- Fix update checker for versions with suffix (hotfix/beta/rc)
- Add collapsing header to Search tab for consistent UI
- Redesign Settings with Android-style grouped cards
- Increase app bar title size (28px) and height (130px)
- Replace all print() with structured logging (logger package)
- Fix lint warnings (curly braces, unnecessary underscores)

lib/utils/logger.dart

@@ -0,0 +1,28 @@
+import 'package:logger/logger.dart';
+
+/// Global logger instance for the app
+/// Uses pretty printer in debug mode for readable output
+final log = Logger(
+  printer: PrettyPrinter(
+    methodCount: 0,
+    errorMethodCount: 5,
+    lineLength: 80,
+    colors: true,
+    printEmojis: true,
+    dateTimeFormat: DateTimeFormat.none,
+  ),
+  level: Level.debug,
+);
+
+/// Logger with class/tag prefix for better traceability
+class AppLogger {
+  final String _tag;
+  
+  AppLogger(this._tag);
+  
+  void d(String message) => log.d('[$_tag] $message');
+  void i(String message) => log.i('[$_tag] $message');
+  void w(String message) => log.w('[$_tag] $message');
+  void e(String message, [Object? error, StackTrace? stackTrace]) => 
+      log.e('[$_tag] $message', error: error, stackTrace: stackTrace);
+}