feat: add Kirigami app skeleton with libmpv playback

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/mpv/mpvitem.h

@@ -0,0 +1,58 @@
+#pragma once
+
+#include <MpvAbstractItem>
+
+#include <QUrl>
+#include <QtQml/qqmlregistration.h>
+
+// QML video surface backed by libmpv (through MpvQt).
+// mpv properties we care about are mirrored as Qt properties so QML can bind to them.
+class MpvItem : public MpvAbstractItem
+{
+    Q_OBJECT
+    QML_ELEMENT
+
+    Q_PROPERTY(QUrl currentUrl READ currentUrl NOTIFY currentUrlChanged)
+    Q_PROPERTY(QString mediaTitle READ mediaTitle NOTIFY mediaTitleChanged)
+    Q_PROPERTY(double position READ position NOTIFY positionChanged)
+    Q_PROPERTY(double duration READ duration NOTIFY durationChanged)
+    Q_PROPERTY(bool paused READ paused WRITE setPaused NOTIFY pausedChanged)
+    Q_PROPERTY(bool fileLoaded READ isFileLoaded NOTIFY fileLoadedChanged)
+
+public:
+    explicit MpvItem(QQuickItem *parent = nullptr);
+    ~MpvItem() override = default;
+
+    QUrl currentUrl() const;
+    QString mediaTitle() const;
+    double position() const;
+    double duration() const;
+    bool paused() const;
+    void setPaused(bool paused);
+    bool isFileLoaded() const;
+
+    Q_INVOKABLE void loadFile(const QUrl &url);
+    Q_INVOKABLE void togglePause();
+    Q_INVOKABLE void seek(double seconds);
+
+Q_SIGNALS:
+    void currentUrlChanged();
+    void mediaTitleChanged();
+    void positionChanged();
+    void durationChanged();
+    void pausedChanged();
+    void fileLoadedChanged();
+
+private:
+    void onPropertyChanged(const QString &property, const QVariant &value);
+    void setFileLoaded(bool loaded);
+
+    bool m_ready = false;
+    QUrl m_pendingUrl;
+    QUrl m_currentUrl;
+    QString m_mediaTitle;
+    double m_position = 0.0;
+    double m_duration = 0.0;
+    bool m_paused = false;
+    bool m_fileLoaded = false;
+};