v3.9.21

fix(log): tick rows kept the stream and the data array in lockstep

- the 10s tick's create path grew the DOM past the 240-line cap

  without trimming old rows, desyncing the row indices the in-place

  stream patches rely on: patches then hit older rows and the log

  visibly jumped back to already-shown content, with full rebuilds

  flickering after that

- the tick path now trims the stream like every other append path

- a fresh panel build lands on the bottom synchronously before the

  next paint instead of flashing the top for one frame