feat(ads): add local interstitial ad dialog widget

- Create a new dialog widget for displaying local interstitial ads
- Implement full-screen dialog with ad image and navigation functionality
- Add close button for dismissing the dialog
- Include error handling for image loading

Author: fulleni

lib/ads/widgets/local_interstitial_ad_dialog.dart

@@ -0,0 +1,90 @@
+import 'package:core/core.dart';
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+import 'package:ui_kit/ui_kit.dart';
+
+/// {@template local_interstitial_ad_dialog}
+/// A dialog widget that displays a [LocalInterstitialAd].
+///
+/// This dialog is designed to be shown as a full-screen overlay,
+/// presenting the ad's image and providing a way to dismiss it or
+/// navigate to the ad's target URL.
+/// {@endtemplate}
+class LocalInterstitialAdDialog extends StatelessWidget {
+  /// {@macro local_interstitial_ad_dialog}
+  const LocalInterstitialAdDialog({
+    required this.localInterstitialAd,
+    super.key,
+  });
+
+  /// The [LocalInterstitialAd] to display.
+  final LocalInterstitialAd localInterstitialAd;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    return Dialog.fullscreen(
+      backgroundColor: theme.colorScheme.surface,
+      child: Stack(
+        children: [
+          Center(
+            child: SingleChildScrollView(
+              child: Column(
+                mainAxisAlignment: MainAxisAlignment.center,
+                children: [
+                  if (localInterstitialAd.imageUrl.isNotEmpty)
+                    Padding(
+                      padding: const EdgeInsets.all(AppSpacing.lg),
+                      child: InkWell(
+                        onTap: () {
+                          // Navigate to the target URL when the ad image is tapped.
+                          // Using context.go to open external URL.
+                          context.go(localInterstitialAd.targetUrl);
+                        },
+                        child: Image.network(
+                          localInterstitialAd.imageUrl,
+                          fit: BoxFit.contain,
+                          errorBuilder: (context, error, stackTrace) =>
+                              const SizedBox.shrink(),
+                        ),
+                      ),
+                    ),
+                  const SizedBox(height: AppSpacing.lg),
+                  Text(
+                    'Local Interstitial Ad',
+                    style: theme.textTheme.titleLarge?.copyWith(
+                      color: theme.colorScheme.onSurface,
+                    ),
+                    textAlign: TextAlign.center,
+                  ),
+                  const SizedBox(height: AppSpacing.md),
+                  Text(
+                    'This is a full-screen advertisement.',
+                    style: theme.textTheme.bodyMedium?.copyWith(
+                      color: theme.colorScheme.onSurfaceVariant,
+                    ),
+                    textAlign: TextAlign.center,
+                  ),
+                ],
+              ),
+            ),
+          ),
+          Positioned(
+            top: AppSpacing.lg,
+            right: AppSpacing.lg,
+            child: IconButton(
+              icon: Icon(
+                Icons.close,
+                color: theme.colorScheme.onSurface,
+              ),
+              onPressed: () {
+                // Dismiss the dialog.
+                Navigator.of(context).pop();
+              },
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}