Drops the legacy Time Gate FFT-windowing feature and the SAW matched-filter
pipeline (SawPipeline, SawDiagnosticWindow, TemplateBuildWorker, and the
associated UI panels/channel modes) to simplify the viewer.
Adds native support for the SRAS v6 file format (scan_format.md), which
scans a different bounding box per angle instead of a uniform AABB. Scan
geometry (n_rows, n_frames, x_start) is now exposed per-angle in SrasFile,
with v2-v5 files populating those arrays uniformly so both formats share
one code path. Waveform data is memory-mapped per angle to handle v6's
ragged layout, and aborted/truncated v6 scans are handled gracefully.
"Pre-process and Save as v5" is disabled for v6 files since the flat v5
layout can't represent per-angle geometry.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>