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/useIntersectionObserver.ts

@@ -10,13 +10,13 @@ export type IntersectionObserverOpts = {
 
 export const getIntersectionObserverEntry = (
   target: Element | Document,
-  entries: IntersectionObserverEntry[]
+  entries: IntersectionObserverEntry[],
 ): IntersectionObserverEntry | undefined => entries.find((entry) => entry.target === target);
 
 export const useIntersectionObserver = (
   onIntersectionCallback: OnIntersectionCallback,
   opts?: IntersectionObserverOpts | (() => IntersectionObserverOpts),
-  observeElement?: Element | null | (() => Element | null)
+  observeElement?: Element | null | (() => Element | null),
 ): IntersectionObserver | undefined => {
   const [intersectionObserver, setIntersectionObserver] = useState<IntersectionObserver>();