Fix two issues preventing HEVC video playback in the web interface:
1. output_file() Content-Range header missing dash separator between
byte range start and end values. The 206 Partial Content response
sent "bytes 04382586/4382587" instead of "bytes 0-4382586/4382587",
which browsers cannot parse, breaking all video streaming via the
files view.
2. Event HLS playback fails for HEVC because video.js VHS detects the
codec as "hvc1" from the fMP4 segment but cannot construct the full
codec string (e.g. "hvc1.1.6.L153.B0") required by
MediaSource.addSourceBuffer(). VHS only knows how to parse avcC
boxes (H.264), not hvcC boxes (HEVC). Use hls.js (already shipped
for live stream views) for HLS event playback instead - it properly
parses HEVC codec info from init segments. Non-HLS events continue
using video.js natively.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>