quickshell: hold tray menu height so switching morphs instead of regrowing

Switching to a tray menu whose items were not currently loaded
collapsed fullHeight at the instant of the switch, so the chrome
morphed DOWN to a stub and replayed the vertical grow when the items
landed, rather than moving across from the previous panel.

An empty Card is not height 0 but 2*cardPad, so loaded-ness has to come
from the model: menuLoaded tracks menuOpener.children. While a newly
assigned menu is loading, fullHeight holds the last loaded height, so
the morph stays continuous and the correction on arrival is small —
nil when it is the same menu as last time.

ui.nix radius knob at 20.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

settings/quickshell.nix

@@ -2108,7 +2108,28 @@ in
                     id: contextMenu
                     property var trayItem: null
                     fullWidth: menuItems.width + 2 * Theme.panelGap
-                    fullHeight: menuItems.height + 2 * Theme.panelGap
+
+                    // While a freshly assigned menu is still loading, the Card
+                    // is empty — and an empty Card is not height 0, it is
+                    // 2*cardPad — so the panel would morph DOWN to a stub and
+                    // then regrow once the items land, instead of moving
+                    // across. Hold the last loaded height until the new items
+                    // arrive so the morph stays continuous. The correction is
+                    // small, and nil when it is the same menu as last time.
+                    readonly property bool menuLoaded:
+                        menuOpener.children && menuOpener.children.values.length > 0
+                    property real lastMenuHeight: 0
+                    fullHeight: (menuLoaded ? menuItems.height
+                                            : Math.max(menuItems.height, lastMenuHeight))
+                                + 2 * Theme.panelGap
+
+                    Connections {
+                        target: menuItems
+                        function onHeightChanged() {
+                            if (contextMenu.menuLoaded)
+                                contextMenu.lastMenuHeight = menuItems.height;
+                        }
+                    }
 
                     // Deliberately NOT cleared on close. Nulling the menu threw
                     // away the loaded items, and the only thing that refills

settings/ui.nix

@@ -12,5 +12,5 @@
 #   Theme.radiusTiny  = radius * 0.5
 #   hyprland decoration.rounding = radius
 {
-  radius = 24;
+  radius = 20;
 }