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/UI/ColorPickerSheet.h

@@ -0,0 +1,68 @@
+#pragma once
+#include "Document/EditorSession.h"
+#include "UI/FloatingPanel.h"
+#include <QLineEdit>
+#include <QPushButton>
+#include <QWidget>
+#include <array>
+#include <functional>
+
+// A picker entry commits on Return or leaving, as Swift's.
+class PickerField : public QLineEdit {
+    Q_OBJECT
+public:
+    PickerField(std::function<void()> commit, std::function<void(int)> step, QWidget *parent);
+
+protected:
+    void keyPressEvent(QKeyEvent *event) override;
+    void focusOutEvent(QFocusEvent *event) override;
+
+private:
+    const std::function<void()> m_commit;
+    const std::function<void(int)> m_step;
+};
+
+// Swift's ColorPickerSheet: field, hue strip, preview, entry.
+class ColorPickerSheet : public QWidget {
+    Q_OBJECT
+public:
+    ColorPickerSheet(EditorSession &session, std::function<void(bool)> finish, QWidget *parent = nullptr);
+
+protected:
+    void paintEvent(QPaintEvent *event) override;
+
+private:
+    // A channel's entry: typed, stepped, clamped, as Swift's row.
+    PickerField *channel(int index);
+    // Swift writes the working hsb; here through the session.
+    void change(const std::function<void(PickerHSB &)> &edit);
+    // The field or strip's pick replaces the channels' typing.
+    void pick(const std::function<void(PickerHSB &)> &edit);
+    void setChannel(int channel, double value);
+    void commitHex();
+    void synchronize();
+
+    EditorSession &m_session;
+    QWidget *const m_field;
+    QWidget *const m_hue;
+    QWidget *const m_preview;
+    // Made first: keys start at R, as the grid reads.
+    const std::array<PickerField *, 3> m_channels;
+    PickerField *const m_hex;
+    QPushButton *const m_ok;
+    QPushButton *const m_cancel;
+};
+
+// Swift's ColorPickerPanelController: the picker in its panel.
+class ColorPickerPanelController {
+public:
+    explicit ColorPickerPanelController(QWidget &owner);
+    void show(const ColorPickerState &state, EditorSession &session);
+    void close();
+    // Hands the keys back to the picker after a sample.
+    static void refocus();
+    static QString identifier() { return QStringLiteral("colorPickerPanel"); }
+
+private:
+    FloatingPanel m_panel;
+};