CLAUDE: item-4 R3 - RT LoG stream into the offline detector (det_rt_log_file) + det_ema_gate sizing stats

New saved param curt.det_rt_log_file: the mode-3 detector consumes a pose-RT
run's -CUAS-RT-LOG detection frames (LoG - avg) instead of its own
subtract-avg+LoG; with the merged stack present and curt_subtract_avg on it
still computes the offline frames and prints the RELATIVE-tol compare
(ruling 3.3 - offline subtracts PRE-LoG, RT subtracts POST-LoG, equal by
linearity except NaN edges) before swapping the RT frames in. No merged
stack = the RT stack ingests as primary input. Outputs tagged -RTLOG;
missing timestamps / synth_src combinations fail LOUD.

det_log_save runs now also accumulate a |LoG-avg| log-histogram and print
the post-LoG noise floor (sigma, p50..p99.99, max) + det_ema_gate
candidates (4/5/6 sigma) and the percentile the current gate admits -
the sizing data ruling 3.1 asked for (dial stays Andrey's).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>