v0.7.0

Add quality ladder, quality picker, rendition details, fast-start path

- HLS ladder 240/360/720p with master playlist; rungs above source skipped
- Player quality selector built from hls.js levels
- Store per-rendition sizes; show source and optimized details in list
- Small h264 MP4s: remux with faststart (or serve original if moov first)
- Remove --optimize-height and --optimize-maxrate (replaced by ladder)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>