ffConvert 1.0.0

First stable release of ffConvert, a GTK4 video converter powered by FFmpeg.

Features:
- Simple two-pane GTKmm 4 interface
- Batch conversion of a folder of videos
- Export to H.264 (MP4), H.265/HEVC (MP4), Avid DNxHR HQX (MOV)
- Optional output scaling
- Progress tracking

Also includes Debian/Ubuntu packaging (CPack 'make deb' target).