chore: upgrade i18next 26, prettier 3, fontsource-variable, domhandler 6, lint-staged 17

- i18next 23->26 + react-i18next 15->17
- prettier 2->3, reformat all files
- replace @fontsource/inter with @fontsource-variable/inter 5, update import path
- domhandler 5->6 (aligns with transitive deps)
- lint-staged 16->17

src/app/components/image-viewer/ImageViewer.tsx

@@ -93,5 +93,5 @@ export const ImageViewer = as<'div', ImageViewerProps>(
         </Box>
       </Box>
     );
-  }
+  },
 );