OmaPhoto 1.0.0: the Linux port of Compositor

A layered image editor for Linux and Omarchy, ported from Compositor
(github.com/robbietilton/Compositor), whose Swift source is its
specification. It reads and writes Compositor's .comp projects.

Packages for Ubuntu, Fedora and Arch come from the release workflow;
scripts/install/ holds one install script per distribution family,
and flake.nix serves NixOS.

Co-Authored-By: Claude <noreply@anthropic.com>

scripts/distro/nixos/Dockerfile

@@ -0,0 +1,3 @@
+# NixOS's package set, through the repository's own flake.
+FROM nixos/nix:latest
+RUN echo "experimental-features = nix-command flakes" >> /etc/nix/nix.conf