Netease's m701/m801.music.126.net CDN RST connections from FFmpeg's
default Lavf UA. The bot's frame loop treats an early ffmpeg exit as
trackEnd and advances the queue, which surfaced as songs auto-skipping
mid-playlist. Add a browser UA + music.163.com Referer for these URLs,
extract args into a tested buildFfmpegArgs(), and harden reconnect
flags (delay_max 5 -> 30, plus reconnect_on_network_error /
reconnect_on_http_error). Verified by A/B running ffmpeg against the
same fresh CDN URL: legacy args got 0 bytes + "End of file" reading
HTTP response; fixed args streamed the full track to completion.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
