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/hooks/useComposingCheck.ts

@@ -13,7 +13,7 @@ export function useCompositionEndTracking(): void {
     (evt: TimeStamped) => {
       setLastCompositionEnd(evt.timeStamp);
     },
-    [setLastCompositionEnd]
+    [setLastCompositionEnd],
   );
 
   useEffect(() => {
@@ -42,6 +42,6 @@ export function useComposingCheck({
       (evt.keyCode === 229 &&
         typeof compositionEnd !== 'undefined' &&
         evt.timeStamp - compositionEnd < compositionEndThreshold),
-    [compositionEndThreshold, compositionEnd]
+    [compositionEndThreshold, compositionEnd],
   );
 }