SeekQuote Web v0.1.9

TikTok movie compatibility
- Adds a silent 44.1 kHz Web Audio track to movie recordings so exported MP4s contain both video and audio streams, matching the structure of the known-working extension export.
- Prefers H.264 + AAC MP4 recording when the browser supports it, with the existing H.264/video-only and WebM fallbacks retained.
- The added audio is silent; music can still be added normally inside TikTok.
- Keeps the existing 30fps rendering, iPhone frame-capture hardening, transitions, and Save Video workflow unchanged.
