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/useTheme.ts

@@ -73,13 +73,13 @@ export const useThemeNames = (): Record<string, string> =>
       [DarkTheme.id]: 'Dark',
       [ButterTheme.id]: 'Butter',
     }),
-    []
+    [],
   );
 
 export const useSystemThemeKind = (): ThemeKind => {
   const darkModeQueryList = useMemo(() => window.matchMedia('(prefers-color-scheme: dark)'), []);
   const [themeKind, setThemeKind] = useState<ThemeKind>(
-    darkModeQueryList.matches ? ThemeKind.Dark : ThemeKind.Light
+    darkModeQueryList.matches ? ThemeKind.Dark : ThemeKind.Light,
   );
 
   useEffect(() => {
@@ -112,8 +112,8 @@ export const useActiveTheme = (): Theme => {
 
   const selectedTheme =
     systemThemeKind === ThemeKind.Dark
-      ? themes.find((theme) => theme.id === darkThemeId) ?? DarkTheme
-      : themes.find((theme) => theme.id === lightThemeId) ?? LightTheme;
+      ? (themes.find((theme) => theme.id === darkThemeId) ?? DarkTheme)
+      : (themes.find((theme) => theme.id === lightThemeId) ?? LightTheme);
 
   return selectedTheme;
 };