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>

src/Document/SelectionEdits.h

@@ -0,0 +1,18 @@
+#pragma once
+#include "Document/BrushStroke.h"
+#include "Document/Selection.h"
+#include <memory>
+
+// Selected pixels being dragged: the lifted raster and the outline.
+class PixelMove {
+public:
+    PixelMove(std::shared_ptr<BrushStroke> raster, DocumentSelection origin, bool duplicate);
+    // The outline shifted by the drag so far.
+    DocumentSelection movedSelection() const;
+
+    // Shared: the canvas draws it while the commit runs.
+    const std::shared_ptr<BrushStroke> raster;
+    const DocumentSelection origin;
+    const bool duplicate;
+    QSizeF offset{0, 0};
+};