Add one-click platform presets to the export dialog that auto-set
resolution, format, and quality for common social media platforms:
- YouTube: 1920x1080, H.264, Very High quality
- TikTok: 1080x1920, H.264, High quality
- Instagram Reels: 1080x1920, H.264, High quality
- Instagram Post: 1080x1080, H.264, High quality
- Twitter/X: 1280x720, H.264, High quality
Selecting a platform preset auto-fills format and quality settings.
Manually changing format or quality resets to Custom mode.
Existing quality presets remain unchanged.
Fixes#737
8a8b9ed6f5