feat: extract subtitle parsing and rendering

static/player/subtitles/vtt.ts

@@ -0,0 +1,38 @@
+export const parseVttTime = (raw: string): number => {
+  const parts = raw.trim().split(':')
+  if (parts.length < 2) return 0
+  const secPart = parts.pop()!
+  const minPart = parts.pop()!
+  const hourPart = parts.pop() ?? '0'
+  return (Number(hourPart) * 3600) + (Number(minPart) * 60) + Number(secPart.replace(',', '.'))
+}
+
+export const parseVttCue = (line: string, lines: string[], i: number) => {
+  if (!line.includes('-->')) return null
+  const [startRaw, endRaw] = line.split('-->')
+  const payload: string[] = []
+  let j = i + 1
+  while (j < lines.length && lines[j].trim() !== '') {
+    payload.push(lines[j]); j++
+  }
+  const text = payload.join('\n').replace(/<[^>]+>/g, '').trim()
+  if (!text) return null
+  return { start: parseVttTime(startRaw), end: parseVttTime(endRaw), text }
+}
+
+export const parseVtt = (text: string) => {
+  const lines = text.replace(/\r/g, '').split('\n')
+  const cues = []
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i].trim()
+    if (!line) continue
+    if (i + 1 < lines.length && !line.includes('-->') && lines[i + 1].includes('-->')) {
+      const cue = parseVttCue(lines[i + 1].trim(), lines, i + 1)
+      if (cue) cues.push(cue); i++
+    } else if (line.includes('-->')) {
+      const cue = parseVttCue(line, lines, i)
+      if (cue) cues.push(cue)
+    }
+  }
+  return cues
+}