feat(legal): bilingual (RU + EN) legal pages with a language + theme switcher

Add English versions of the privacy policy, EULA and offer (ui/legal/*_en.md) and render each legal page as one self-contained bilingual document: both language bodies plus a header language toggle and theme toggle (no back), a small inline ES5 script that switches language client-side (no reload, default Russian + persisted) and applies the theme (system default + persisted override) — mirroring the landing. The offer's English view transliterates the Russian product names spliced from the live catalog.

renderLegalHtml now takes both language sources; renderOffer splices the price list into both; the renderer bakes and reads the _en sources and pre-renders the static pages at boot. Also wrap the /offer/ contour probe in the same retry+timeout as the legal probe (the offer page is now bilingual and larger). Docs + renderer/ui tests updated.

renderer/src/legal.mjs

@@ -1,21 +1,24 @@
-// The public legal pages (GET /privacy/, GET /eula/): the owner-edited markdown under ui/legal/,
-// rendered by the SAME shared renderLegalHtml the offer uses (bundled from ui/src/lib/offer). Unlike
-// the offer, these carry no dynamic data — no backend fetch, no marker splice. Kept out of server.mjs
-// so the per-page title/canonical presets are unit-testable without HTTP (test/legal.test.mjs).
+// The public legal pages (GET /privacy/, GET /eula/): the owner-edited RU + EN markdown under
+// ui/legal/, rendered by the SAME shared renderLegalHtml the offer uses (bundled from ui/src/lib/offer)
+// into one bilingual page with a language + theme switcher. Unlike the offer, these carry no dynamic
+// data — no backend fetch, no marker splice. Kept out of server.mjs so the per-page title/canonical
+// presets are unit-testable without HTTP (test/legal.test.mjs).
 import { renderLegalHtml } from '../dist/gameimage.mjs';
 
-// renderPrivacy renders the privacy-policy markdown as the standalone /privacy/ page.
-export function renderPrivacy(markdown) {
-  return renderLegalHtml(markdown, {
-    title: 'Политика конфиденциальности — Эрудит',
+// renderPrivacy renders the privacy-policy markdown (RU + EN) as the standalone /privacy/ page.
+export function renderPrivacy(ruMd, enMd) {
+  return renderLegalHtml({
+    ru: { md: ruMd, title: 'Политика конфиденциальности — Эрудит' },
+    en: { md: enMd, title: 'Privacy Policy — Erudit' },
     canonical: 'https://erudit-game.ru/privacy/',
   });
 }
 
-// renderEula renders the end-user licence agreement markdown as the standalone /eula/ page.
-export function renderEula(markdown) {
-  return renderLegalHtml(markdown, {
-    title: 'Пользовательское соглашение — Эрудит',
+// renderEula renders the end-user licence agreement markdown (RU + EN) as the standalone /eula/ page.
+export function renderEula(ruMd, enMd) {
+  return renderLegalHtml({
+    ru: { md: ruMd, title: 'Пользовательское соглашение — Эрудит' },
+    en: { md: enMd, title: 'Terms of Use — Erudit' },
     canonical: 'https://erudit-game.ru/eula/',
   });
 }