feat: season title card on cold start

Shows "SEASON 1 / First Bloom / N stages" over the season background for
~1.6s between splash and home; tap anywhere skips. Bails to home on
content-load error. Adds seasonLabel/seasonStages l10n keys (en + ko).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/l10n/app_en.arb

@@ -28,5 +28,14 @@
         "type": "int"
       }
     }
+  },
+  "seasonLabel": "SEASON",
+  "seasonStages": "{count} stages",
+  "@seasonStages": {
+    "placeholders": {
+      "count": {
+        "type": "int"
+      }
+    }
   }
 }

lib/l10n/app_ko.arb

@@ -14,5 +14,7 @@
   "playAgain": "다시 하기",
   "nextStage": "다음 스테이지",
   "streakMilestone": "{days}일 연속 플레이! 대단해요!",
-  "almostThere": "{percent}% 달성!"
+  "almostThere": "{percent}% 달성!",
+  "seasonLabel": "SEASON",
+  "seasonStages": "{count}개 스테이지"
 }

lib/ui/screens/season_title_screen.dart

@@ -0,0 +1,111 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import '../../l10n/gen/app_localizations.dart';
+import '../../state/providers.dart';
+import '../widgets/season_background.dart';
+import 'home_screen.dart';
+
+/// Cold-start interstitial: "SEASON 1 · First Bloom". Tap anywhere or wait
+/// ~1.6s. If content somehow fails to load we bail straight to home.
+class SeasonTitleScreen extends ConsumerStatefulWidget {
+  const SeasonTitleScreen({super.key});
+
+  @override
+  ConsumerState<SeasonTitleScreen> createState() =>
+      _SeasonTitleScreenState();
+}
+
+class _SeasonTitleScreenState extends ConsumerState<SeasonTitleScreen> {
+  Timer? _auto;
+  bool _navigated = false;
+  bool _dataTimerArmed = false;
+
+  void _go() {
+    if (_navigated || !mounted) return;
+    _navigated = true;
+    Navigator.of(context).pushReplacement(
+      MaterialPageRoute(builder: (_) => const HomeScreen()),
+    );
+  }
+
+  @override
+  void dispose() {
+    _auto?.cancel();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final seasons = ref.watch(seasonsProvider);
+    final l10n = AppLocalizations.of(context)!;
+    return seasons.when(
+      loading: () {
+        _auto ??= Timer(const Duration(milliseconds: 2500), _go);
+        return const Scaffold(
+            backgroundColor: Color(0xFF0E1430), body: SizedBox());
+      },
+      error: (e, st) {
+        WidgetsBinding.instance.addPostFrameCallback((_) => _go());
+        return const Scaffold(
+            backgroundColor: Color(0xFF0E1430), body: SizedBox());
+      },
+      data: (list) {
+        if (!_dataTimerArmed) {
+          _dataTimerArmed = true;
+          _auto?.cancel();
+          _auto = Timer(const Duration(milliseconds: 1600), _go);
+        }
+        final pack = list.first;
+        final locale = Localizations.localeOf(context).languageCode;
+        final number = int.tryParse(pack.seasonId.split('_').last) ?? 1;
+        return GestureDetector(
+          behavior: HitTestBehavior.opaque,
+          onTap: _go,
+          child: Scaffold(
+            body: Stack(
+              fit: StackFit.expand,
+              children: [
+                SeasonBackground(theme: pack.theme),
+                SafeArea(
+                  child: Column(
+                    mainAxisAlignment: MainAxisAlignment.center,
+                    children: [
+                      Text(
+                        '${l10n.seasonLabel} $number',
+                        style: TextStyle(
+                          letterSpacing: 6,
+                          fontSize: 14,
+                          color: Colors.white.withValues(alpha: 0.7),
+                        ),
+                      ),
+                      const SizedBox(height: 10),
+                      Text(
+                        pack.titleFor(locale),
+                        style: const TextStyle(
+                          fontSize: 38,
+                          fontWeight: FontWeight.w900,
+                          color: Colors.white,
+                        ),
+                      ),
+                      const SizedBox(height: 8),
+                      Text(
+                        l10n.seasonStages(pack.stages.length),
+                        style: TextStyle(
+                          fontSize: 14,
+                          color: Colors.white.withValues(alpha: 0.6),
+                        ),
+                      ),
+                    ],
+                  ),
+                ),
+              ],
+            ),
+          ),
+        );
+      },
+    );
+  }
+}

lib/ui/screens/splash_screen.dart

@@ -1,8 +1,8 @@
 import 'package:flutter/material.dart';
 
-import 'home_screen.dart';
+import 'season_title_screen.dart';
 
-Widget _defaultNextScreen() => const HomeScreen();
+Widget _defaultNextScreen() => const SeasonTitleScreen();
 
 /// Logo-assembly splash: four glossy blocks fly in to form a 2x2 mark, the
 /// wordmark fades in, then we hand off. SaveRepository is already opened in

test/ui/season_title_screen_test.dart

@@ -0,0 +1,68 @@
+import 'package:block_seasons/data/save_repository.dart';
+import 'package:block_seasons/game/models/season.dart';
+import 'package:block_seasons/game/models/stage.dart';
+import 'package:block_seasons/l10n/gen/app_localizations.dart';
+import 'package:block_seasons/state/providers.dart';
+import 'package:block_seasons/ui/screens/home_screen.dart';
+import 'package:block_seasons/ui/screens/season_title_screen.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+SeasonPack _pack() => SeasonPack(
+      schemaVersion: 1,
+      seasonId: 'season_001',
+      version: 1,
+      title: const {'en': 'First Bloom', 'ko': '첫 개화'},
+      theme: SeasonTheme.fallback,
+      stages: [
+        StageConfig(
+          id: 's1',
+          seed: 1,
+          moveLimit: 10,
+          preset: const [],
+          objectives: const [],
+          stars: const StarThresholds(twoMovesLeft: 2, threeMovesLeft: 4),
+          generatorProfile: 'mid',
+        ),
+      ],
+    );
+
+Widget _app(SaveRepository repo) => ProviderScope(
+      overrides: [
+        saveRepositoryProvider.overrideWithValue(repo),
+        seasonsProvider.overrideWith((ref) async => [_pack()]),
+      ],
+      child: const MaterialApp(
+        localizationsDelegates: AppLocalizations.localizationsDelegates,
+        supportedLocales: AppLocalizations.supportedLocales,
+        home: SeasonTitleScreen(),
+      ),
+    );
+
+void main() {
+  testWidgets('shows season title then auto-advances to home',
+      (tester) async {
+    SharedPreferences.setMockInitialValues({});
+    final repo = SaveRepository(await SharedPreferences.getInstance());
+    await tester.pumpWidget(_app(repo));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 100));
+    expect(find.text('First Bloom'), findsOneWidget);
+    await tester.pump(const Duration(seconds: 2));
+    await tester.pumpAndSettle();
+    expect(find.byType(HomeScreen), findsOneWidget);
+  });
+
+  testWidgets('tap skips immediately', (tester) async {
+    SharedPreferences.setMockInitialValues({});
+    final repo = SaveRepository(await SharedPreferences.getInstance());
+    await tester.pumpWidget(_app(repo));
+    await tester.pump();
+    await tester.pump(const Duration(milliseconds: 100));
+    await tester.tap(find.text('First Bloom'));
+    await tester.pumpAndSettle();
+    expect(find.byType(HomeScreen), findsOneWidget);
+  });
+}