Daysish 0.1.0: first builds for Linux, Windows and macOS

The first Daysish release is on the Portal: AppImage, deb and rpm for Linux, an installer for Windows, and a signed, notarized universal build for macOS. Every bundle comes straight from the release workflow, no hand-uploads anywhere.

Windows shows a SmartScreen warning until the download builds a reputation. That is expected for an unsigned build and goes away once signing lands.