checkCommandQueue runs processCommand on its own thread, which read
`now` and frame_count and wrote last_frame_sent (CMD_PAUSE) and
got_command while the streaming loop writes or reads them.
ThreadSanitizer reports these as data races (zm_monitorstream.cpp
processCommand and runStream's got_command read against the command
thread, and checkCommandQueue's `now` read against EventStream::runStream).
Make frame_count, last_frame_sent and got_command atomic, as #4939 did
for the playback state, and have the command thread read the clock
itself instead of the loop's `now`. The status reply's fps and delay are
then measured against the current time rather than the start of the
loop's last pass. Test: [races] case for the frame bookkeeping, for TSan
builds.
fixes#5230
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
