[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/dialogs/dlg_tournament_settings.cpp

@@ -0,0 +1,48 @@
+#include "dlg_tournament_settings.h"
+
+#include <QDialogButtonBox>
+#include <QFormLayout>
+#include <QLabel>
+#include <QPushButton>
+#include <QSpinBox>
+
+DlgTournamentSettings::DlgTournamentSettings(QWidget *parent) : QDialog(parent)
+{
+    setWindowTitle(tr("Tournament Settings"));
+
+    auto *mainLayout = new QFormLayout(this);
+
+    gamesPerMatchSpin = new QSpinBox(this);
+    gamesPerMatchSpin->setRange(1, 5);
+    gamesPerMatchSpin->setValue(1);
+    gamesPerMatchSpin->setToolTip(tr("Number of games per match (e.g., 3 for Best of 3)"));
+    mainLayout->addRow(tr("Games per match:"), gamesPerMatchSpin);
+
+    QLabel *hintLabel = new QLabel(tr("Set to 3 for Best of 3, 5 for Best of 5, etc."), this);
+    hintLabel->setStyleSheet("color: palette(placeholderText);");
+    mainLayout->addRow(QString(), hintLabel);
+
+    buttonBox = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel, this);
+    connect(buttonBox, &QDialogButtonBox::accepted, this, &DlgTournamentSettings::actOK);
+    connect(buttonBox, &QDialogButtonBox::rejected, this, &QDialog::reject);
+    mainLayout->addRow(buttonBox);
+
+    setFixedHeight(sizeHint().height());
+}
+
+DlgTournamentSettingsResult DlgTournamentSettings::getResult() const
+{
+    DlgTournamentSettingsResult result;
+    result.gamesPerMatch = gamesPerMatchSpin->value();
+    return result;
+}
+
+void DlgTournamentSettings::setCurrentGamesPerMatch(int n)
+{
+    gamesPerMatchSpin->setValue(n);
+}
+
+void DlgTournamentSettings::actOK()
+{
+    accept();
+}