plugins: stipe dupe plugin previews & add fallback support

quickshell/Modules/Settings/PluginCard.qml

@@ -13,7 +13,8 @@ DCard {
     property bool installed: false
     property bool selected: false
     property string fallbackIcon: "extension"
-    property string previewSource: PluginService.previewUrl(plugin)
+    property string previewSource: PluginService.thumbUrl(plugin)
+    property string previewFallback: PluginService.previewUrl(plugin)
     property var badges: PluginService.badgeModel(plugin)
     property bool allowUninstall: false
     property var palette: null
@@ -50,12 +51,20 @@ DCard {
 
             CachingImage {
                 id: cardPreview
+
+                property bool useFallback: false
+
                 anchors.fill: parent
-                imagePath: root.previewSource
+                imagePath: useFallback ? root.previewFallback : root.previewSource
                 maxCacheSize: 640
                 fillMode: Image.PreserveAspectCrop
                 animate: false
                 visible: status === Image.Ready
+                onStatusChanged: {
+                    if (status !== Image.Error || useFallback || !root.previewFallback || root.previewFallback === root.previewSource)
+                        return;
+                    useFallback = true;
+                }
             }
 
             DIcon {

quickshell/Modules/Settings/ThemeBrowser.qml

@@ -372,6 +372,7 @@ RegistryBrowserWindow {
                     busy: !!root.pendingThemes[cardCell.modelData.id]
                     fallbackIcon: "palette"
                     previewSource: root.themePreviewUrl(cardCell.modelData)
+                    previewFallback: ""
                     badges: root.themeBadges(cardCell.modelData)
                     palette: root.themePalette(cardCell.modelData)
                     allowUninstall: true

quickshell/Services/PluginService.qml

@@ -1294,6 +1294,17 @@ Singleton {
         return plugin.screenshot || "";
     }
 
+    // 16:10 screenshot-only render; the full preview card bakes in title text the card already shows
+    function thumbUrl(plugin) {
+        if (!plugin)
+            return "";
+        if (plugin.thumbUrl)
+            return plugin.thumbUrl;
+        if (plugin.id)
+            return previewApiBase + plugin.id + "/thumb";
+        return "";
+    }
+
     function heroUrl(plugin) {
         if (!plugin)
             return "";