feat(wallpapers): add image crop support and i18n strings

Adds per-image image-crop support with persistent settings.
Rendering adapts to crop mode, zoom and position per image.
Locales the UI strings and notifications; app name updated.

- Cropping workflow with per-image crop state and rendering
- Localizes strings and notifications for en and de
- Introduces set_image_crop command and its permission schema

plugins/src/desktop.rs

@@ -38,15 +38,15 @@ impl<R: Runtime> Wallpaper<R> {
             .enumerate()
             .skip(payload.offset)
             .take(payload.limit)
-                .map(|(index, url)| GalleryImage {
-                    id: format!("demo-{index}"),
-                    url,
-                    selected: index == 0,
-                    crop_mode: "cover".into(),
-                    crop_zoom: 1.0,
-                    crop_position_x: 0.5,
-                    crop_position_y: 0.5,
-                })
+            .map(|(index, url)| GalleryImage {
+                id: format!("demo-{index}"),
+                url,
+                selected: index == 0,
+                crop_mode: "cover".into(),
+                crop_zoom: 1.0,
+                crop_position_x: 0.5,
+                crop_position_y: 0.5,
+            })
             .collect();
         Ok(GalleryPage { total: 3, items })
     }