Let the menu fill 70% of the screen

The row list was capped at 60% of screen height so a card could never read
as a page. On a laptop-height display that folds the starting menu one row
early, hiding About behind the peek for no gain.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

shell/plugins/menu/Menu.qml

@@ -158,7 +158,7 @@ Item {
     // a longer submenu scrolls behind the fold instead of growing the card.
     if (panel.maxRowsHeight >= 0) available = Math.min(available, panel.maxRowsHeight)
     // A card that swallows the whole screen reads as a page, not a menu.
-    return Math.min(available, Math.round(panel.height * 0.6))
+    return Math.min(available, Math.round(panel.height * 0.7))
   }
 
   // When every row fits, the list gets its full height. When they don't,