Add empty state, gamepad task controls, and X: Close

Show a PlaceholderMessage in the grid when no games are found,
with context-aware text for empty library vs no search results.

Map gamepad A to activate and X to close in RunningGamesView.
Update the legend bar to show X: Close when running tasks are
visible.

containments/homescreens/folio/qml/gaming/GameCenterOverlay.qml

@@ -100,10 +100,17 @@ Window {
                 if (grid.activeFocus) grid.moveCurrentIndexRight()
                 break
             case GamingShell.GamepadManager.ButtonA:
-                if (grid.activeFocus && grid.currentItem) {
+                if (runningGames.activeFocus) {
+                    runningGames.activateCurrent()
+                } else if (grid.activeFocus && grid.currentItem) {
                     root.launchGame(grid.currentIndex)
                 }
                 break
+            case GamingShell.GamepadManager.ButtonX:
+                if (runningGames.activeFocus) {
+                    runningGames.closeCurrent()
+                }
+                break
             case GamingShell.GamepadManager.ButtonB:
                 root.dismissRequested()
                 break
@@ -388,6 +395,19 @@ Window {
                 highlightMoveDuration: 0
                 highlight: null
 
+                Kirigami.PlaceholderMessage {
+                    anchors.centerIn: parent
+                    width: parent.width - Kirigami.Units.gridUnit * 4
+                    visible: grid.count === 0 && !GamingShell.GameLauncherProvider.loading
+                    icon.name: "games-none"
+                    text: searchField.text.length > 0
+                          ? i18n("No games match your search")
+                          : i18n("No games found")
+                    explanation: searchField.text.length > 0
+                                 ? ""
+                                 : i18n("Install games or check that they have the Game category in their .desktop file")
+                }
+
                 onActiveFocusChanged: {
                     if (activeFocus && count > 0 && currentIndex < 0) {
                         currentIndex = 0
@@ -567,7 +587,9 @@ Window {
 
                 // Gamepad legend
                 PC3.Label {
-                    text: i18n("A: Select  B: Back  Y: Exit  LB/RB: Filter  ☰: Search")
+                    text: runningGames.hasTasks
+                          ? i18n("A: Select  X: Close  B: Back  Y: Exit  LB/RB: Filter  ☰: Search")
+                          : i18n("A: Select  B: Back  Y: Exit  LB/RB: Filter  ☰: Search")
                     font.pointSize: Kirigami.Theme.defaultFont.pointSize * 0.75
                     opacity: 0.5
                 }

containments/homescreens/folio/qml/gaming/RunningGamesView.qml

@@ -29,6 +29,19 @@ Item {
         taskList.forceActiveFocus()
     }
 
+    function activateCurrent() {
+        if (taskList.currentItem) {
+            taskList.currentItem.activate()
+        }
+    }
+
+    function closeCurrent() {
+        if (taskList.currentItem) {
+            var idx = taskList.currentIndex
+            tasks.requestClose(tasks.makeModelIndex(idx))
+        }
+    }
+
     TaskManager.VirtualDesktopInfo { id: vdInfo }
     TaskManager.ActivityInfo    { id: actInfo }