- oakengine_export_render_ex covers the dialog's entire option surface
(formats, codecs, pix fmts, audio params, ranges incl. still frame,
subtitles, scaling, threads, custom OCIO color transform names,
per-codec key/value options) - zero feature reduction
- the dialog's Start now creates a FacadeExportTask that drives
oakengine_export_render_ex instead of constructing ExportTask in the
UI; progress flows through the facade callback and cancel through
oakengine_export_cancel (OAKENGINE_E_CANCELLED preserves the
keep-dialog-open semantics)
- two real fixes: audio sample format 0 no longer means an
AAC-unsupported u8_p (default is f32_p), and image-sequence exports
use the engine's real [#####] placeholder instead of a made-up -%04d