Adds muxl.RunMuxlSegmenterEvents (rich-event variant of RunMuxlSegmenter: delivers *MuxlEvent with catalog + per-track inits + durations/sample counts, the unsigned counterpart of RunMuxlSignSegment) and livehls.Run, which drives it into a live HLS Writer — appending the init and each canonical segment to a growing fMP4 and indexing per-track byte ranges. End-to-end test runs a fragmented fMP4 fixture through the wasm segmenter: 2 tracks, 4 segments, valid byte ranges + live playlists. rust/muxl-wasm points at the local ../muxl (path dep) and muxl.wasm is rebuilt from it (the eli/muxl-refactor branch — new verbs + audio-only 1s fix). NOTE: temporary local-build setup; pin a muxl git rev before merge. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>