[Client] Sync conflict dialog, onboarding and conflict default

cockatrice/src/interface/widgets/dialogs/dlg_sync_conflict.h

@@ -0,0 +1,63 @@
+/**
+ * @file dlg_sync_conflict.h
+ * @brief Dialog for resolving a deck that changed both locally and on the server.
+ */
+
+#ifndef DLG_SYNC_CONFLICT_H
+#define DLG_SYNC_CONFLICT_H
+
+#include "../../deck_sync/deck_sync_conflict.h"
+
+#include <QDialog>
+#include <QString>
+#include <libcockatrice/deck_list/deck_diff.h>
+
+class QCheckBox;
+class QLabel;
+class QListWidget;
+class QRadioButton;
+
+/**
+ * @class DlgSyncConflict
+ * @brief Shows both versions of a conflicted deck and returns the verdict.
+ *
+ * Radio choice between Keep mine / Keep server (newest preselected), Keep both
+ * and Use merge (enabled only when the changes touch disjoint cards). The
+ * change list shows card-count deltas between the two versions; the merge
+ * summary describes the auto-merge proposal. Rejected dialogs resolve as Skip.
+ */
+class DlgSyncConflict : public QDialog
+{
+    Q_OBJECT
+public:
+    explicit DlgSyncConflict(const DeckSyncConflict &conflict, QWidget *parent = nullptr);
+    [[nodiscard]] DeckSyncResolution resolution() const;
+    void retranslateUi();
+
+private slots:
+    void updateRememberBoxes();
+
+private:
+    DeckSyncResolutionAction selectedAction() const;
+
+    DeckSyncConflict conflict;
+    bool decksParsed = false;
+    bool localIsNewer = true;
+    DeckDiffResult shownChanges;
+    bool mergeable = false;
+    int mergedMainCount = 0;
+    int mergedSideCount = 0;
+
+    QLabel *titleLabel;
+    QLabel *detailLabel;
+    QRadioButton *keepMineRadio;
+    QRadioButton *keepServerRadio;
+    QRadioButton *keepBothRadio;
+    QRadioButton *mergeRadio;
+    QListWidget *changesList;
+    QLabel *mergeSummaryLabel;
+    QCheckBox *rememberSessionBox;
+    QCheckBox *rememberAlwaysBox;
+};
+
+#endif // DLG_SYNC_CONFLICT_H