Polish README for launch: badges, comparison table, hero layout (#23)

- Add macOS 15.0+, license (CC0), and platform badges
- Add hero screenshot at top for immediate visual impact
- Add comparison table vs Cyberduck, Transmit, FileZilla
- Arrange screenshots in 2x2 grid layout
- Fix macOS version requirement from 13.0 to 15.0 (matches deployment target)
- Fix license reference from MIT to CC0 1.0 Universal
- Update Xcode prerequisite to 16.0

Co-authored-by: Paperclip <noreply@paperclip.ing>

fix duplicate connection s3

fix build number and release

add support for dynamic versioning

correcting the github url

prepare for release v0.2.1

added streamlined usage

prepare for release v0.2.1

bump up the version

improved icon selector with more options