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/arch/Dockerfile

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+# Arch and Omarchy: Qt, GCC and ONNX Runtime as shipped.
+FROM archlinux:latest
+RUN pacman -Syu --noconfirm --needed base-devel cmake ninja pkgconf qt6-base qt6-imageformats libheif libde265 \
+        fontconfig onnxruntime-cpu ttf-dejavu curl \
+    && pacman -Scc --noconfirm
+# U²-Net for Remove Background, pinned by its checksum.
+RUN mkdir -p /usr/local/share/omaphoto \
+    && curl -fsSL -o /usr/local/share/omaphoto/u2net.onnx \
+        https://github.com/danielgatis/rembg/releases/download/v0.0.0/u2net.onnx \
+    && echo "8d10d2f3bb75ae3b6d527c77944fc5e7dcd94b29809d47a739a7a728a912b491  /usr/local/share/omaphoto/u2net.onnx" | sha256sum -c -

scripts/distro/fedora/Dockerfile

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+# Fedora's own Qt and ONNX Runtime; HEVC from RPM Fusion.
+FROM fedora:42
+RUN dnf install -y https://mirrors.rpmfusion.org/free/fedora/rpmfusion-free-release-42.noarch.rpm \
+    && dnf install -y gcc-c++ cmake ninja-build pkgconf qt6-qtbase-devel qt6-qtimageformats libheif-devel libheif-freeworld \
+        fontconfig-devel onnxruntime-devel dejavu-sans-fonts dejavu-serif-fonts dejavu-sans-mono-fonts curl rpm-build file \
+    && dnf clean all
+# U²-Net for Remove Background, pinned by its checksum.
+RUN mkdir -p /usr/local/share/omaphoto \
+    && curl -fsSL -o /usr/local/share/omaphoto/u2net.onnx \
+        https://github.com/danielgatis/rembg/releases/download/v0.0.0/u2net.onnx \
+    && echo "8d10d2f3bb75ae3b6d527c77944fc5e7dcd94b29809d47a739a7a728a912b491  /usr/local/share/omaphoto/u2net.onnx" | sha256sum -c -

scripts/distro/nixos/Dockerfile

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+# 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