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/install/ubuntu.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# Installs OmaPhoto's latest DEB on Ubuntu and its derivatives.
+set -euo pipefail
+base=https://github.com/ZacharyZhang-NY/OmaPhoto/releases/latest/download
+package=omaphoto_amd64.deb
+. /etc/os-release
+case " ${ID:-} ${ID_LIKE:-} " in
+*" ubuntu "*) ;;
+*)
+    echo "This script is for Ubuntu and its derivatives; this system is ${PRETTY_NAME:-unknown}." >&2
+    exit 1
+    ;;
+esac
+if [ "$(uname -m)" != x86_64 ]; then
+    echo "OmaPhoto's packages are built for x86_64 alone." >&2
+    exit 1
+fi
+work=$(mktemp -d)
+trap 'rm -rf "$work"' EXIT
+curl -fL --proto '=https' -o "$work/$package" "$base/$package"
+curl -fsSL --proto '=https' -o "$work/SHA256SUMS" "$base/SHA256SUMS"
+# The package must match the checksum published beside it.
+(cd "$work" && grep " $package\$" SHA256SUMS | sha256sum -c -)
+# apt reads the file as its own user.
+chmod a+rx "$work"
+sudo apt-get install -y "$work/$package"