feat: コンテスト名をProblemモデルに追加し、詳細画面に表示する処理を実装

Author: yuubinnkyoku

lib/models/problem.dart

@@ -1,6 +1,7 @@
 class Problem {
   final String title;
   final String contestId;
+  final String contestName;
   final String statement;
   final String constraints;
   final String inputFormat;
@@ -11,6 +12,7 @@ class Problem {
   Problem({
     required this.title,
     required this.contestId,
+    required this.contestName,
     required this.statement,
     required this.constraints,
     required this.inputFormat,

lib/screens/problem_detail_screen.dart

@@ -290,6 +290,17 @@ class _ProblemDetailScreenState extends State<ProblemDetailScreen> {
             child: Column(
               crossAxisAlignment: CrossAxisAlignment.start,
               children: [
+                if (problem.contestName.isNotEmpty && problem.contestName != 'コンテスト名が見つかりません')
+                  Padding(
+                    padding: const EdgeInsets.only(bottom: 8.0),
+                    child: Text(
+                      problem.contestName,
+                      style: TextStyle(
+                        fontSize: 14,
+                        color: Theme.of(context).colorScheme.onSurfaceVariant,
+                      ),
+                    ),
+                  ),
                 TexWidget(
                   content: problem.title,
                   textStyle: const TextStyle(

lib/services/atcoder_service.dart

@@ -28,6 +28,10 @@ class AtCoderService {
         // コンテストIDの取得
         final contestId = _extractContestId(url);
 
+        // コンテスト名の取得
+        final contestTitleElement = document.querySelector('.contest-title');
+        final contestName = contestTitleElement?.text.trim() ?? 'コンテスト名が見つかりません';
+
         // デバッグ: HTMLの構造を調査
         developer.log("HTML構造の分析を開始...");
         _analyzeHtmlStructure(document);
@@ -86,6 +90,7 @@ class AtCoderService {
         return Problem(
           title: title,
           contestId: contestId,
+          contestName: contestName,
           statement: statement,
           constraints: constraints,
           inputFormat: inputFormat,