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/useAccountManagement.ts

@@ -10,7 +10,7 @@ export const useAccountManagementActions = () => {
       accountDeactivate: 'org.matrix.account_deactivate',
       crossSigningReset: 'org.matrix.cross_signing_reset',
     }),
-    []
+    [],
   );
 
   return actions;