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/typing-indicator/TypingIndicator.tsx

@@ -21,5 +21,5 @@ export const TypingIndicator = as<'div', TypingIndicatorProps>(
       <span className={css.TypingDot({ size, index: '1', animated: !disableAnimation })} />
       <span className={css.TypingDot({ size, index: '2', animated: !disableAnimation })} />
     </Box>
-  )
+  ),
 );