hoverpanel: add 400ms grace period on show, increase hide debounce to 150ms

modules/HoverPanel.qml

@@ -67,16 +67,33 @@ PanelWindow {
         panelContainer.x = Math.max(0, Math.min(Math.round(cx - root.contentWidth / 2), sw - root.contentWidth));
     }
 
+    // Grace period: after _show(), suppress auto-close briefly so Niri has time
+    // to route wl_pointer.enter to the new overlay surface (cursor may be stationary).
+    property bool _grace: false
+    Timer {
+        id: _graceTimer
+        interval: 400
+        onTriggered: {
+            root._grace = false;
+            if (!root.showPanel)
+                root.dismiss();
+        }
+    }
+
     function _show() {
         _updatePosition();
         _winVisible = true;
         hideAnim.stop();
         showAnim.start();
+        _grace = true;
+        _graceTimer.restart();
     }
 
     function dismiss() {
         showAnim.stop();
         hideAnim.start();
+        _grace = false;
+        _graceTimer.stop();
     }
 
     Component.onCompleted: if (popupMode)
@@ -84,8 +101,8 @@ PanelWindow {
 
     Timer {
         id: _hideTimer
-        interval: 50
-        onTriggered: if (!root.showPanel)
+        interval: 150
+        onTriggered: if (!root.showPanel && !root._grace)
             root.dismiss()
     }