refactor(core): keep plan prices, cloud quotas and public URLs in one contract (WS-A)

Prices, quotas and site URLs were copied by hand into the edge functions,
admin, desktop and the landing site, and the copies disagreed (Payple billed
9,900/29,900 KRW, admin labels said 12,900/24,900 KRW and $9.9/$19.9, the
site said 2,900/8,900 KRW).

- packages/core/src/plan-catalog.ts is the single source for PLAN_PRICE_KRW
  (Free 0 / Pro 2,900 / Pro+ 8,900 a month) and PLAN_QUOTA.
- packages/core/src/web-urls.ts is the single source for the public origin,
  the /app web-app base path, SITE_URLS and billingUrl().
- Deno cannot bundle packages/core, so scripts/ci/sync-core-contract.mjs
  generates _shared/core-contract.generated.ts; `npm run contract:check`
  fails on drift (same pattern as version:sync).
- Payple checkout, renewal and webhook amount checks now bill the catalog
  price, so existing subscribers move to the new price at their next renewal.
  quota.ts, team-contract.ts and the tests read the generated values.
- Admin MRR/ARR is computed in KRW from the catalog; license labels, the
  release link and desktop PREMIUM_LLM limits derive from core; the site
  imports prices and quotas directly.

Policy: docs/REFACTOR_POLICY.md Wave 3, W3-1 and W3-2.

apps/admin/src/app/(admin)/page.tsx

@@ -22,11 +22,12 @@ export default async function AdminOverviewPage(): Promise<React.ReactElement> {
     }
   }
 
+  const krw = new Intl.NumberFormat('ko-KR', { style: 'currency', currency: 'KRW', maximumFractionDigits: 0 })
   const revenueCards = revenue
     ? [
         {
           title: 'Annual Recurring Revenue',
-          value: `$${revenue.arrUsd.toLocaleString()}`,
+          value: krw.format(revenue.arrKrw),
           subtext: 'Active subscriptions × 12 months',
           color: 'green' as const,
           badge: 'ARR',
@@ -34,7 +35,7 @@ export default async function AdminOverviewPage(): Promise<React.ReactElement> {
         },
         {
           title: 'Monthly Recurring Revenue',
-          value: `$${revenue.mrrUsd.toLocaleString()}`,
+          value: krw.format(revenue.mrrKrw),
           subtext: `Pro ${revenue.tierBreakdown.pro.toLocaleString()} · Pro+ ${revenue.tierBreakdown.pro_plus.toLocaleString()}`,
           color: 'blue' as const,
           badge: 'MRR',
@@ -208,7 +209,7 @@ export default async function AdminOverviewPage(): Promise<React.ReactElement> {
               >
                 <Box sx={{ display: 'flex', justifyContent: 'space-between', alignItems: 'flex-start', mb: 2 }}>
                   <StatRing color={card.color} size={46}>
-                    <Typography sx={{ fontFamily: FONT_MONO, fontSize: '13px', fontWeight: 500 }}>$</Typography>
+                    <Typography sx={{ fontFamily: FONT_MONO, fontSize: '13px', fontWeight: 500 }}>₩</Typography>
                   </StatRing>
                   <Box component="span" sx={statusBadgeSx(card.badgeColor)}>
                     {card.badge}

apps/admin/src/app/(admin)/releases/page.tsx

@@ -3,6 +3,7 @@
 
 import { Box, Typography, Button } from '@mui/material'
 import { DoubleBezelCard, TactileBadge } from '@d3ro/ui/components/ds'
+import { SITE_URLS } from '@d3ro/core/web-urls'
 import { C, FONT_SANS, FONT_MONO, panelSx, tableSx, statusBadgeSx } from '@/lib/console-theme'
 import { requireManager } from '@/lib/admin-guard'
 import { fetchReleaseHub, type ReleaseAssetPlatform, type ReleaseHub } from '@/lib/forgejo-releases'
@@ -107,7 +108,7 @@ function HeaderBar({ feedLive, repoHtmlUrl }: { feedLive: boolean; repoHtmlUrl:
           Forgejo Releases ↗
         </Button>
         <Button
-          href="https://d3ro.chanpaca.net/download.html"
+          href={SITE_URLS.download}
           target="_blank"
           variant="outlined"
           sx={{