fix(dock): align multitask view to first app gap with app icon spacing

Add leftPadding to TaskManager to compensate for the multitask view's
implicit width being wider than its icon, ensuring the visual gap
matches appTitleSpacing.

为TaskManager添加leftPadding属性，补偿多任务视图的宽度大于其图标
本身所产生的视觉偏移，使多任务视图与首个驻留应用的间距与应用图标
间距保持一致。

Log: 修复任务栏多任务视图与首个应用图标间距不一致的问题
PMS: BUG-364263
Influence: 多任务视图按钮与首个驻留应用图标的间距现在与应用图标之间的间距一致，视觉上更加统一。

Author: Ivy233

panels/dock/taskmanager/package/TaskManager.qml

@@ -16,13 +16,23 @@ ContainmentItem {
     property int dockOrder: 16
     property real remainingSpacesForTaskManager: Panel.rootObject.dockRemainingSpaceForCenter 
     readonly property int appTitleSpacing: Math.max(10, Math.round(Panel.rootObject.dockItemMaxSize * 9 / 14) / 3)
+    // Start padding for the app container so that the visual gap
+    // (multitask icon right edge → first app icon left edge) = appTitleSpacing.
+    // Compensates for the multitask view's box being wider than its icon.
+    readonly property real multitaskViewIconRatio: 0.8
+    readonly property real iconWidthToMaxSizeRatio: 9 / 14
+    readonly property real startPadding: Math.max(0, appTitleSpacing - (Panel.rootObject.dockItemMaxSize * (multitaskViewIconRatio - iconWidthToMaxSizeRatio) / 2))
 
     implicitWidth: {
-        let maxW = Panel.itemAlignment === Dock.LeftAlignment ? Math.max(remainingSpacesForTaskManager, appContainer.implicitWidth) : Math.min(remainingSpacesForTaskManager, appContainer.implicitWidth)
+        let extra = useColumnLayout ? 0 : startPadding
+        let w = appContainer.implicitWidth + extra
+        let maxW = Panel.itemAlignment === Dock.LeftAlignment ? Math.max(remainingSpacesForTaskManager, w) : Math.min(remainingSpacesForTaskManager, w)
         return useColumnLayout ? Panel.rootObject.dockSize : maxW
     }
     implicitHeight: {
-        let maxH = Panel.itemAlignment === Dock.LeftAlignment ? Math.max(remainingSpacesForTaskManager, appContainer.implicitHeight) : Math.min(remainingSpacesForTaskManager, appContainer.implicitHeight)
+        let extra = useColumnLayout ? startPadding : 0
+        let h = appContainer.implicitHeight + extra
+        let maxH = Panel.itemAlignment === Dock.LeftAlignment ? Math.max(remainingSpacesForTaskManager, h) : Math.min(remainingSpacesForTaskManager, h)
         return useColumnLayout ? maxH : Panel.rootObject.dockSize
     }
     // Helper function to find the current index of an app by its appId in the visualModel
@@ -72,6 +82,8 @@ ContainmentItem {
     OverflowContainer {
         id: appContainer
         anchors.fill: parent
+        anchors.leftMargin: useColumnLayout ? 0 : taskmanager.startPadding
+        anchors.topMargin: useColumnLayout ? taskmanager.startPadding : 0
         useColumnLayout: taskmanager.useColumnLayout
         spacing: taskmanager.appTitleSpacing
         remove: Transition {