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/server.mjs

@@ -24,21 +24,22 @@ const PORT = Number(process.env.RENDERER_PORT || 8090);
 // A render request is a finished game's journal — generously capped.
 const MAX_BODY = 2 * 1024 * 1024;
 
-// The offer prose is baked into the image (renderer/Dockerfile) and read once at boot; only the
-// price list is dynamic (fetched per request). The backend endpoint is internal (off the edge
-// allow-list) and serves the tables from its in-memory cache. RENDERER_OFFER_MD overrides the baked
-// path for a local run (point it at ../ui/legal/offer_ru.md).
-const OFFER_MD = readFileSync(process.env.RENDERER_OFFER_MD || new URL('../legal/offer_ru.md', import.meta.url), 'utf8');
-// The privacy policy (GET /privacy/) and EULA (GET /eula/): static owner-edited markdown, read once at
-// boot, no dynamic data. RENDERER_PRIVACY_MD / RENDERER_EULA_MD override the baked path for a local run.
-const PRIVACY_MD = readFileSync(process.env.RENDERER_PRIVACY_MD || new URL('../legal/privacy_ru.md', import.meta.url), 'utf8');
-const EULA_MD = readFileSync(process.env.RENDERER_EULA_MD || new URL('../legal/eula_ru.md', import.meta.url), 'utf8');
-// Render the static legal pages once at boot and serve the cached HTML: they carry no dynamic data,
-// and re-parsing the large EULA markdown on every request is slow enough under deploy-time host
-// contention (the renderer is CPU/memory-capped) to flake the contour probe. The offer stays
-// per-request because it splices in the live price list.
-const PRIVACY_HTML = renderPrivacy(PRIVACY_MD);
-const EULA_HTML = renderEula(EULA_MD);
+// Each legal page is bilingual (RU + EN); both markdown sources are baked into the image
+// (renderer/Dockerfile) and read once at boot. The offer's price list is the only dynamic part
+// (fetched per request from the backend's internal endpoint and spliced in); privacy + eula carry no
+// dynamic data. The RENDERER_*_MD / RENDERER_*_EN_MD env vars override the baked paths for a local run.
+const rd = (p) => readFileSync(p, 'utf8');
+const OFFER_MD = rd(process.env.RENDERER_OFFER_MD || new URL('../legal/offer_ru.md', import.meta.url));
+const OFFER_EN_MD = rd(process.env.RENDERER_OFFER_EN_MD || new URL('../legal/offer_en.md', import.meta.url));
+const PRIVACY_MD = rd(process.env.RENDERER_PRIVACY_MD || new URL('../legal/privacy_ru.md', import.meta.url));
+const PRIVACY_EN_MD = rd(process.env.RENDERER_PRIVACY_EN_MD || new URL('../legal/privacy_en.md', import.meta.url));
+const EULA_MD = rd(process.env.RENDERER_EULA_MD || new URL('../legal/eula_ru.md', import.meta.url));
+const EULA_EN_MD = rd(process.env.RENDERER_EULA_EN_MD || new URL('../legal/eula_en.md', import.meta.url));
+// Render the static legal pages once at boot and serve the cached HTML: re-parsing the large EULA on
+// every request is slow enough under deploy-time host contention (the renderer is CPU/memory-capped)
+// to flake the contour probe. The offer stays per-request because it splices in the live price list.
+const PRIVACY_HTML = renderPrivacy(PRIVACY_MD, PRIVACY_EN_MD);
+const EULA_HTML = renderEula(EULA_MD, EULA_EN_MD);
 const OFFER_PRICING_URL =
   (process.env.RENDERER_BACKEND_URL || 'http://backend:8080') + '/api/v1/internal/offer/pricing';
 
@@ -82,7 +83,7 @@ const server = createServer(async (req, res) => {
       return;
     }
     if (req.method === 'GET' && path === '/offer/') {
-      const html = renderOffer(OFFER_MD, await fetchOfferPricing());
+      const html = renderOffer(OFFER_MD, OFFER_EN_MD, await fetchOfferPricing());
       res
         .writeHead(200, { 'content-type': 'text/html; charset=utf-8', 'cache-control': 'no-cache' })
         .end(html);