Improve toolbar and player tab UI restrictions

Main toolbar is now non-movable, non-floatable, and restricted to top/bottom areas with context menu disabled for a more consistent UI. In the players tab, the player group box is hidden when no players exist to create a seamless placeholder appearance, and shown when players are present.

Author: Chickaboo

src/gambitpairing/gui/mainwindow.py

@@ -246,6 +246,16 @@ def _setup_toolbar(self):
         Icons are loaded from the system theme for a native look and feel.
         """
         toolbar = self.addToolBar("Main Toolbar")
+        # Prevent detaching / floating
+        toolbar.setMovable(False)
+        try:
+            toolbar.setFloatable(False)
+        except Exception:
+            pass
+        toolbar.setAllowedAreas(
+            Qt.ToolBarArea.TopToolBarArea | Qt.ToolBarArea.BottomToolBarArea
+        )  # restrict just in case
+        toolbar.setContextMenuPolicy(Qt.ContextMenuPolicy.PreventContextMenu)
         toolbar.setIconSize(QtCore.QSize(24, 24))
         toolbar.setStyleSheet("""
             QToolBar {

src/gambitpairing/gui/players_tab.py

@@ -581,9 +581,12 @@ def _update_visibility(self):
                 self.no_players_placeholder.show()
                 self.table_players.hide()
                 self.btn_add_player_detail.hide()  # Hide until first player is added
+                # Hide the group box frame/title to create seamless wall look
+                self.player_group.hide()
             else:
                 # Tournament with players: show table and add button
                 self.no_players_placeholder.hide()
+                self.player_group.show()
                 self.table_players.show()
                 self.btn_add_player_detail.show()
                 tournament_started = len(self.tournament.rounds_pairings_ids) > 0