fix: improve notification bubble panel hide animation

Changed the bubble panel visibility logic to include a 400ms delay
before hiding when there are no notifications. This prevents the panel
from disappearing abruptly when the last bubble is removed. The QML
ListView now includes a remove transition with smooth exit animation
for bubbles.

Added QTimer include for delayed hide functionality. Modified the
ListView height calculation to use maximum of contentHeight and
childrenRect.height to ensure proper layout during animations.
Implemented a sequential animation for bubble removal with x-axis slide-
out effect.

Log: Improved notification bubble animations with smoother hide effects

Influence:
1. Test notification bubble appearance and disappearance
2. Verify panel remains visible during bubble removal animations
3. Check that multiple bubbles animate correctly
4. Test edge cases with rapid notification additions/removals
5. Verify panel properly hides after all bubbles are removed
6. Test animation timing and smoothness

PMS: BUG-284659

Author: caimc123456

panels/notification/bubble/bubblepanel.cpp

@@ -12,6 +12,7 @@
 #include <QQueue>
 
 #include <appletbridge.h>
+#include <qtimer.h>
 
 namespace notification {
 Q_DECLARE_LOGGING_CATEGORY(notifyLog)
@@ -110,7 +111,14 @@ void BubblePanel::onNotificationStateChanged(qint64 id, int processedType)
 void BubblePanel::onBubbleCountChanged()
 {
     bool isEmpty = m_bubbles->items().isEmpty();
-    setVisible(!isEmpty && enabled());
+    const bool visible = !isEmpty && enabled();
+    if (!visible) {
+        QTimer::singleShot(400, this, [this]() {
+            setVisible(false);
+        });
+    } else {
+        setVisible(visible);
+    }
 }
 
 void BubblePanel::addBubble(qint64 id)

panels/notification/bubble/package/Bubble.qml

@@ -12,6 +12,27 @@ Control {
     id: control
     height: loader.height
     property var bubble
+
+    ListView.onRemove: SequentialAnimation {
+        PropertyAction {
+            target: control
+            property: "ListView.delayRemove"
+            value: true
+        }
+        NumberAnimation {
+            target: control
+            property: "x"
+            to: 360
+            duration: 400
+            easing.type: Easing.InExpo
+        }
+        PropertyAction {
+            target: control
+            property: "ListView.delayRemove"
+            value: false
+        }
+    }
+
     onHoveredChanged: function () {
         if (control.hovered) {
             Applet.bubbles.delayRemovedBubble = bubble.id