[Client] Add tournament UI for creating and following lobby tournaments

Wires the tournament protocol into the client:
- DlgCreateGame gains a tournament checkbox with a games-per-match
  settings sub-dialog; both values are sent with Command_CreateGame and
  mirrored in the join-info variant of the dialog
- TournamentWidget renders live standings (with deck-submission state)
  and pairings for the local player's perspective, and asks to open the
  current match game via openMatchGameRequested()
- TournamentTabGameExtension attaches an overview page to TabGame's
  stacked views, mirrors phase and submission progress onto a deck-view
  status strip, and provides round-trip navigation between game view and
  standings; hosts get an in-game settings dialog during deck building
- Open-match falls back to joining as spectator through TabSupervisor;
  sub-games now return to their parent tab on close, falling back to
  the normal leave-game flow when the parent is gone

cockatrice/src/interface/widgets/draft/tournament_widget.h

@@ -0,0 +1,56 @@
+#ifndef TOURNAMENT_WIDGET_H
+#define TOURNAMENT_WIDGET_H
+
+#include <QWidget>
+#include <libcockatrice/protocol/pb/event_tournament_state.pb.h>
+
+class QLabel;
+class QPushButton;
+class QTableWidget;
+class QTableWidgetItem;
+
+/**
+ * @class TournamentWidget
+ * @ingroup GameViews
+ * @brief Displays live standings and pairings for a tournament game.
+ *
+ * Updated exclusively via updateTournamentState(); the widget holds no
+ * logic of its own beyond mapping protocol state to table rows. Navigation
+ * decisions (which pairing belongs to the local player) are resolved here so
+ * callers only need to react to openMatchGameRequested().
+ */
+class TournamentWidget : public QWidget
+{
+    Q_OBJECT
+public:
+    explicit TournamentWidget(QWidget *parent = nullptr);
+
+    void updateTournamentState(const Event_TournamentState &state);
+    void setLocalPlayerId(int playerId);
+    void retranslateUi();
+
+signals:
+    /*! Emitted when the user asks to open the match game of their current pairing. */
+    void openMatchGameRequested(int gameId);
+
+private:
+    void rebuildTables(const Event_TournamentState &state);
+    void resolveCurrentGameId(const Event_TournamentState &state);
+    void updateOpenMatchButton();
+    [[nodiscard]] QString getPlayerName(const Event_TournamentState &state, int playerId) const;
+    [[nodiscard]] int getGamesPerMatch(const Event_TournamentState &state) const;
+
+    QLabel *statusLabel;
+    QLabel *roundLabel;
+    QTableWidget *standingsTable;
+    QTableWidget *pairingsTable;
+    QPushButton *openMatchButton;
+
+    int localPlayerId = -1;
+    int currentGameId = -1;
+    bool hasOwnLivePairing = false;
+    bool hasAnyLivePairing = false;
+    Event_TournamentState lastState;
+};
+
+#endif // TOURNAMENT_WIDGET_H