feat(legal): wire recurrent-payments document + restore footer link

Backend now serves a dedicated recurring-payments legal document, so:
- Add adminLegalPagesApi.get/updateRecurrentPayments and infoApi.getRecurrentPayments
  (+ InfoVisibility.recurrent).
- AdminLegalPages: new 'Рекуррентные платежи' editor tab (DocumentEditor now driven
  by a DOCUMENT_API dispatch map instead of privacy/offer ternaries).
- PublicLegal: add 'recurrent' doc; add public /recurrent-payments route.
- Re-add the recurrent link to the login LegalFooter (was removed pending backend).
- i18n: admin.legalPages.tabs.recurrent for ru/en/fa/zh (footer.recurrent already existed).

type-check, eslint, prettier and build all pass.

src/App.tsx

@@ -269,6 +269,7 @@ function App() {
         <Route path="/reset-password" element={<ResetPassword />} />
         <Route path="/offer" element={<PublicLegal doc="offer" />} />
         <Route path="/privacy" element={<PublicLegal doc="privacy" />} />
+        <Route path="/recurrent-payments" element={<PublicLegal doc="recurrent" />} />
         <Route
           path="/merge/:mergeToken"
           element={