添加繁体转简体，简体转繁体功能

web/src/utils/subtitleChinese.ts

@@ -0,0 +1,30 @@
+export type SubtitleChineseMode = 'original' | 'simplified' | 'traditional'
+
+type ChineseConverter = (text: string) => string
+
+const identity: ChineseConverter = (text) => text
+
+export function normalizeSubtitleChineseMode(value: unknown): SubtitleChineseMode {
+  return value === 'simplified' || value === 'traditional' ? value : 'original'
+}
+
+let simplifiedConverter: Promise<ChineseConverter> | undefined
+let traditionalConverter: Promise<ChineseConverter> | undefined
+
+export function loadSubtitleChineseConverter(
+  mode: SubtitleChineseMode,
+): Promise<ChineseConverter> {
+  if (mode === 'original') return Promise.resolve(identity)
+
+  if (mode === 'simplified') {
+    simplifiedConverter ??= import('opencc-js/t2cn').then(({ Converter }) =>
+      Converter({ from: 't', to: 'cn' }),
+    )
+    return simplifiedConverter
+  }
+
+  traditionalConverter ??= import('opencc-js/cn2t').then(({ Converter }) =>
+    Converter({ from: 'cn', to: 'tw' }),
+  )
+  return traditionalConverter
+}