chore: update appcast for v1.6.2

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

chore: update appcast for v1.6.1

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

chore: update appcast for v1.6.0

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

chore: update appcast for v1.5.0

docs: update README download button and license to GPLv3

fix: prevent preview panel from staying visible after hover exit

fix: rebuild v1.1.0 with correct version in binary

feat: add GitHub release update checker on launch

feat: add app icon and README with screenshots