feat(ui): add themed shell navigation

lib/widgets/app_shell.dart

@@ -0,0 +1,68 @@
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+class AppShell extends StatelessWidget {
+  const AppShell({
+    required this.child,
+    required this.currentLocation,
+    super.key,
+  });
+
+  final Widget child;
+  final String currentLocation;
+
+  @override
+  Widget build(BuildContext context) {
+    final selectedIndex = currentLocation.startsWith('/settings') ? 1 : 0;
+
+    return Scaffold(
+      body: DecoratedBox(
+        decoration: BoxDecoration(
+          gradient: LinearGradient(
+            begin: Alignment.topCenter,
+            end: Alignment.bottomCenter,
+            colors: [
+              Theme.of(context).scaffoldBackgroundColor,
+              Theme.of(context).colorScheme.surface,
+            ],
+          ),
+        ),
+        child: SafeArea(bottom: false, child: child),
+      ),
+      bottomNavigationBar: SafeArea(
+        top: false,
+        child: Padding(
+          padding: const EdgeInsets.fromLTRB(16, 0, 16, 16),
+          child: ClipRRect(
+            borderRadius: BorderRadius.circular(24),
+            child: NavigationBar(
+              selectedIndex: selectedIndex,
+              onDestinationSelected: (index) {
+                switch (index) {
+                  case 0:
+                    context.go('/devices');
+                    break;
+                  case 1:
+                    context.go('/settings');
+                    break;
+                }
+              },
+              destinations: const [
+                NavigationDestination(
+                  icon: Icon(Icons.bluetooth_searching_outlined),
+                  selectedIcon: Icon(Icons.bluetooth_searching),
+                  label: 'Devices',
+                ),
+                NavigationDestination(
+                  icon: Icon(Icons.settings_outlined),
+                  selectedIcon: Icon(Icons.settings),
+                  label: 'Settings',
+                ),
+              ],
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}

lib/widgets/horizontal_scanning_animation.dart

@@ -12,7 +12,7 @@ class HorizontalScanningAnimation extends StatefulWidget {
     this.height = 50.0,
   });
   @override
-  _HorizontalScanningAnimationState createState() =>
+  State<HorizontalScanningAnimation> createState() =>
       _HorizontalScanningAnimationState();
 }
 
@@ -117,8 +117,6 @@ class _HorizontalWavePainter extends CustomPainter {
       double currentWidth =
           width * easedProgress * 0.8; // Max 80% width expansion
       double startX = (width / 2) - (currentWidth / 2);
-      double endX = (width / 2) + (currentWidth / 2);
-
       // Calculate opacity based on progress (fade in and out)
       double opacity;
       if (waveProgress < 0.1) {
@@ -130,8 +128,9 @@ class _HorizontalWavePainter extends CustomPainter {
       }
       opacity = max(0.0, opacity); // Clamp opacity
 
-      if (opacity <= 0.0 || currentWidth < 5)
-        continue; // Skip drawing if invisible or too small
+      if (opacity <= 0.0 || currentWidth < 5) {
+        continue;
+      }
 
       // Create the wave path
       final path = Path();

lib/widgets/scanning_animation.dart

@@ -16,7 +16,7 @@ class ScanningWaveAnimation extends StatefulWidget {
   });
 
   @override
-  _ScanningWaveAnimationState createState() => _ScanningWaveAnimationState();
+  State<ScanningWaveAnimation> createState() => _ScanningWaveAnimationState();
 }
 
 class _ScanningWaveAnimationState extends State<ScanningWaveAnimation> {