Problem: with the Source monitor focused, L only ever played at normal
speed, and J and the slow shuttle commands returned "Source playback
currently supports normal forward speed": the Source clock always ran at 1x.
Fix: the Source clock runs at a signed speed. L/J play forward/backward
and pressing the same key again doubles the speed up to 8x; Shuttle Slow
Right/Left play at 1/4 speed. As in the Program monitor, speeds other than
normal forward play without sound, and backward playback stops on the
first frame. docs/monitors.md updated.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>