feat: configurable intro/credits marker regex patterns

Add settings to customize regex patterns for matching intro and credits
markers in chapter titles, with the current hardcoded values as defaults.
Also reclassifies real markers with non-standard type strings against the
configured patterns.

lib/i18n/strings_zh.g.dart

@@ -297,6 +297,11 @@ class _TranslationsSettingsZh implements TranslationsSettingsEn {
 	@override String get autoSkipCreditsDescription => '自动跳过片尾并播放下一集';
 	@override String get autoSkipDelay => '自动跳过延迟';
 	@override String autoSkipDelayDescription({required Object seconds}) => '自动跳过前等待 ${seconds} 秒';
+	@override String get introPattern => '片头标记模式';
+	@override String get introPatternDescription => '用于匹配章节标题中片头标记的正则表达式';
+	@override String get creditsPattern => '片尾标记模式';
+	@override String get creditsPatternDescription => '用于匹配章节标题中片尾标记的正则表达式';
+	@override String get invalidRegex => '无效的正则表达式';
 	@override String get downloads => '下载';
 	@override String get downloadLocationDescription => '选择下载内容的存储位置';
 	@override String get downloadLocationDefault => '默认（应用存储）';
@@ -1472,6 +1477,11 @@ extension on TranslationsZh {
 			'settings.autoSkipCreditsDescription' => '自动跳过片尾并播放下一集',
 			'settings.autoSkipDelay' => '自动跳过延迟',
 			'settings.autoSkipDelayDescription' => ({required Object seconds}) => '自动跳过前等待 ${seconds} 秒',
+			'settings.introPattern' => '片头标记模式',
+			'settings.introPatternDescription' => '用于匹配章节标题中片头标记的正则表达式',
+			'settings.creditsPattern' => '片尾标记模式',
+			'settings.creditsPatternDescription' => '用于匹配章节标题中片尾标记的正则表达式',
+			'settings.invalidRegex' => '无效的正则表达式',
 			'settings.downloads' => '下载',
 			'settings.downloadLocationDescription' => '选择下载内容的存储位置',
 			'settings.downloadLocationDefault' => '默认（应用存储）',
@@ -1811,13 +1821,13 @@ extension on TranslationsZh {
 			'liveTv.noPrograms' => '没有可用的节目数据',
 			'liveTv.channelNumber' => ({required Object number}) => '频道 ${number}',
 			'liveTv.live' => '直播',
+			_ => null,
+		} ?? switch (path) {
 			'liveTv.hd' => '高清',
 			'liveTv.premiere' => '新',
 			'liveTv.reloadGuide' => '重新加载节目指南',
 			'liveTv.allChannels' => '所有频道',
 			'liveTv.now' => '现在',
-			_ => null,
-		} ?? switch (path) {
 			'liveTv.today' => '今天',
 			'liveTv.midnight' => '午夜',
 			'liveTv.overnight' => '凌晨',