wallpapers: add fallback magick thumbnailer script

.config/quickshell/ii/services/Wallpapers.qml

@@ -15,6 +15,7 @@ Singleton {
     id: root
 
     property string thumbgenScriptPath: `${FileUtils.trimFileProtocol(Directories.scriptPath)}/thumbnails/thumbgen.py`
+    property string generateThumbnailsMagicScriptPath: `${FileUtils.trimFileProtocol(Directories.scriptPath)}/thumbnails/generate-thumbnails-magick.sh`
     property string directory: FileUtils.trimFileProtocol(`${Directories.pictures}/Wallpapers`)
     property alias folderModel: folderModel // Expose for direct binding when needed
     property string searchQuery: ""
@@ -124,9 +125,8 @@ Singleton {
         thumbgenProc.directory = root.directory
         thumbgenProc.running = false
         thumbgenProc.command = [
-            thumbgenScriptPath,
-            "--size", size,
-            "-d", `${root.directory}`
+            "bash", "-c",
+            `${thumbgenScriptPath} --size ${size} -d ${root.directory} || ${generateThumbnailsMagicScriptPath} --size ${size} -d ${root.directory}`,
         ]
         thumbgenProc.running = true
     }