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/scroll-top-container/ScrollTopContainer.tsx

@@ -27,10 +27,10 @@ export const ScrollTopContainer = as<
           onVisibilityChange?.(entry.isIntersecting);
         }
       },
-      [anchorRef, onVisibilityChange]
+      [anchorRef, onVisibilityChange],
     ),
     useCallback(() => ({ root: scrollRef?.current }), [scrollRef]),
-    useCallback(() => anchorRef.current, [anchorRef])
+    useCallback(() => anchorRef.current, [anchorRef]),
   );
 
   if (onTop) return null;