- ExportSettings: container format, video/audio codecs, size/fps/
bitrate, bit depth (8/10 → U8/U10), SDR 709 + HDR 2020 code points,
export range
- AppEngine::start_export_with(settings, path); real builds the
task params via encoding_params_with_settings (codec tables gate
each container — a non-supporting combo errors, never silently
defaults; the one menu only offers compatible codecs)
- oak-task EncodingParams: video_bit_rate / audio_bit_rate +
color_override_enabled + primaries/trc/space (override wins over
the project's delivery colorspace)
- mock start_export_with (no-op fake progress)
The dialog UI rebuild (fields + container→codec→color enability
linking) follows in the next unit.