feat(offer): live catalog price list in the public offer, served by the render sidecar

Robokassa moderation requires the public offer to list every digital good with
its price. Move /offer/ off the static landing container to the render sidecar:
it splices the live catalog price list (§4.4) into the owner-edited
ui/legal/offer_ru.md and renders it with the shared ui/src/lib/offer.ts — one
renderer, no drift, always matching the current catalog with no redeploy.

- backend: /api/v1/internal/offer/pricing (internal, off the edge allow-list)
  projects the active catalog into two markdown tables — chip packs priced per
  rail (roubles / VK votes / Telegram Stars) and chip-priced values — through
  payments.Money so no float reaches the page. Cached in memory: warmed at boot,
  marked stale on every catalog mutation, so a served render issues no query.
- renderer: GET /offer/ fetches the tables and substitutes them at the
  <#pricing_template#> marker, then renders; offer_ru.md is baked into the image
  and marked is bundled from ui. GET /offer -> 301. Only /offer/ is edge-exposed.
- caddy: route /offer/ to the sidecar; drop the now-dead landing /offer/
  handlers and the vite emit-offer plugin.
- offer: fill §4.3 (the chip-payment wording) and drop the in-page back link.
- landing footer: a feedback link (the offer's Telegram contact) beside the
  offer link.
- docs (ARCHITECTURE, FUNCTIONAL +_ru, renderer README), CI /offer/ probe,
  unit + integration + node tests.

renderer/src/entry.ts

@@ -1,6 +1,9 @@
-// The esbuild bundle entry: re-exports the SHARED game-image renderer from ui/src/lib —
-// the exact module the browser build unit-tests — plus the alphabet cache seeder the
-// server fills from the backend-supplied per-variant table. Bundled by `pnpm run bundle`
-// into dist/gameimage.mjs (type erasure only; the ui project type-checks the source).
+// The esbuild bundle entry: re-exports the SHARED ui/src/lib modules — the exact modules the
+// browser build unit-tests — so the sidecar runs them on the server. Bundled by `pnpm run bundle`
+// into dist/gameimage.mjs (type erasure only; the ui project type-checks the source):
+//   - drawGameImage + setAlphabet: the finished-game PNG export (POST /render).
+//   - renderOfferHtml: the public-offer page (GET /offer/) — the same renderer the landing build
+//     used to invoke, now server-side so the live catalog price list can be spliced in.
 export { drawGameImage, type RenderOptions } from '../../ui/src/lib/gameimage';
 export { setAlphabet } from '../../ui/src/lib/alphabet';
+export { renderOfferHtml } from '../../ui/src/lib/offer';