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/message/FileHeader.tsx

@@ -36,7 +36,7 @@ export function FileDownloadButton({ filename, url, mimeType, encInfo }: FileDow
       const fileURL = URL.createObjectURL(fileContent);
       FileSaver.saveAs(fileURL, filename);
       return fileURL;
-    }, [mx, url, useAuthentication, mimeType, encInfo, filename])
+    }, [mx, url, useAuthentication, mimeType, encInfo, filename]),
   );
 
   const downloading = downloadState.status === AsyncStatus.Loading;
@@ -52,8 +52,8 @@ export function FileDownloadButton({ filename, url, mimeType, encInfo }: FileDow
         downloading
           ? 'Downloading...'
           : hasError
-          ? 'Download failed, click to retry'
-          : 'Download file'
+            ? 'Download failed, click to retry'
+            : 'Download file'
       }
     >
       {downloading ? (