feat: add back button

lib/views/pin_lock_view.dart

@@ -19,6 +19,7 @@ class PinEntryView extends StatefulWidget {
   final Future<bool> Function(String)? onVerify;
   final Future<bool> Function(String)? onSet;
   final String? Function()? errorMessage;
+  final bool showBack;
 
   const PinEntryView({
     super.key,
@@ -28,6 +29,7 @@ class PinEntryView extends StatefulWidget {
     this.onVerify,
     this.onSet,
     this.errorMessage,
+    this.showBack = false,
   });
 
   @override
@@ -182,6 +184,18 @@ class _PinEntryViewState extends State<PinEntryView> {
           padding: const EdgeInsets.symmetric(horizontal: 24),
           child: Column(
             children: [
+              if (widget.showBack) ...[
+                const Spacer(flex: 1),
+                Row(
+                  children: [
+                    IconButton(
+                      onPressed: () => {},
+                      icon: const Icon(Icons.close),
+                      tooltip: 'Back',
+                    ),
+                  ],
+                ),
+              ],
               const Spacer(flex: 2),
               Icon(Icons.lock_outline_rounded, size: 36, color: scheme.primary),
               const SizedBox(height: 16),