Dosyaload & Vidmixi / Dizipal HLS Proxy Worker v3

Endpoints:
  /play?id={embedId}     → HLS stream (m3u8 rewritten & signed)
  /extract?id={embedId}  → JSON {m3u8Url, subtitles}
  /m3u8?u={base64}       → Sub-playlist proxy
  /ts?u={base64}         → Segment proxy
  /vtt?u={base64}        → Subtitle proxy