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.

ui/vite.config.ts

@@ -3,7 +3,6 @@ import { resolve } from 'node:path';
 import { defineConfig, type Plugin } from 'vite';
 import { svelte } from '@sveltejs/vite-plugin-svelte';
 import { VitePWA } from 'vite-plugin-pwa';
-import { renderOfferHtml } from './src/lib/offer';
 
 /**
  * injectBootVersion stamps the app version into index.html's boot-capability guard, replacing its
@@ -39,22 +38,6 @@ function emitPolyfills(): Plugin {
   };
 }
 
-/**
- * emitOffer renders the public offer markdown (legal/offer_ru.md) to a standalone
- * static page and emits it as dist/offer/index.html, which the landing container
- * serves at /offer/ (deploy/landing/Caddyfile). The markdown is the owner-editable
- * source of truth, so the page is regenerated from it on every build.
- */
-function emitOffer(): Plugin {
-  return {
-    name: 'emit-offer',
-    generateBundle() {
-      const md = readFileSync(resolve(import.meta.dirname, 'legal/offer_ru.md'), 'utf8');
-      this.emitFile({ type: 'asset', fileName: 'offer/index.html', source: renderOfferHtml(md) });
-    },
-  };
-}
-
 // The edge Connect service is scrabble.edge.v1.Gateway; the gateway serves it over
 // h2c on :8081 by default. In dev we proxy the RPC path so the browser (which can
 // not speak h2c directly) talks to the dev server on the same origin. In `mock`
@@ -77,7 +60,6 @@ export default defineConfig(({ mode }) => ({
   plugins: [
     svelte(),
     emitPolyfills(),
-    emitOffer(),
     injectBootVersion(),
     // App-shell precache for the offline mode: a custom (injectManifest) service worker precaches
     // index.html + the hashed assets so the installed web PWA cold-launches with no network. It