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/useTextAreaCodeEditor.ts

@@ -6,7 +6,7 @@ import { GetTarget } from '../plugins/text-area/type';
 
 export const useTextAreaCodeEditor = (
   textAreaRef: MutableRefObject<HTMLTextAreaElement | null>,
-  intentSpaceCount: number
+  intentSpaceCount: number,
 ) => {
   const getTarget: GetTarget = useCallback(() => {
     const target = textAreaRef.current;