fix：第一轮跑

lib/features/ads/presentation/splash_ad_dialog.dart

@@ -0,0 +1,82 @@
+import 'dart:async';
+import 'package:flutter/material.dart';
+
+import '../application/splash_ad_controller.dart';
+import 'ad_media.dart';
+
+enum SplashAdResult { clicked, skipped, completed }
+
+class SplashAdDialog extends StatefulWidget {
+  const SplashAdDialog({
+    super.key,
+    required this.entry,
+    required this.onClick,
+    required this.onShown,
+  });
+  final SplashAdEntry entry;
+  final Future<void> Function() onClick;
+  final VoidCallback onShown;
+  @override
+  State<SplashAdDialog> createState() => _SplashAdDialogState();
+}
+
+class _SplashAdDialogState extends State<SplashAdDialog> {
+  Timer? timer;
+  late int remain;
+  bool opening = false;
+  @override
+  void initState() {
+    super.initState();
+    remain = widget.entry.ad.countdownSeconds.clamp(1, 5);
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      widget.onShown();
+    });
+    timer = Timer.periodic(const Duration(seconds: 1), (_) {
+      if (remain <= 1) {
+        Navigator.of(context).pop(SplashAdResult.completed);
+      } else if (mounted) {
+        setState(() => remain--);
+      }
+    });
+  }
+
+  @override
+  void dispose() {
+    timer?.cancel();
+    super.dispose();
+  }
+
+  Future<void> open() async {
+    if (opening) return;
+    opening = true;
+    timer?.cancel();
+    await widget.onClick();
+    if (mounted) Navigator.of(context).pop(SplashAdResult.clicked);
+  }
+
+  @override
+  Widget build(BuildContext context) => Material(
+    color: Colors.black,
+    child: Stack(
+      children: [
+        Positioned.fill(
+          child: GestureDetector(
+            onTap: open,
+            child: AdMedia(
+              ad: widget.entry.ad,
+              assetPath: widget.entry.assetPath,
+            ),
+          ),
+        ),
+        Positioned(
+          top: MediaQuery.paddingOf(context).top + 16,
+          right: 18,
+          child: FilledButton(
+            onPressed: () => Navigator.of(context).pop(SplashAdResult.skipped),
+            child: Text('跳过 ${remain}s'),
+          ),
+        ),
+      ],
+    ),
+  );
+}