docs(developers): spell out the Reown allowed-origins requirement

The blank WalletConnect QR on staging is the relay rejecting the origin:
the Reown project's allowlist only contains the *-widget.shapeshift.com
demo hosts, and the same project ID is baked into the website bundle.
Nothing in this repo can fix that; document exactly what to add and how
to check the current list, and note the new host-owned AppKit init.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: 0xApotheosis

app/[lang]/developers/README.md

@@ -24,7 +24,9 @@ This directory contains the `/developers` landing page: the entry point for dApp
 ## Technical Implementation
 
 - Most copy lives in `app/[lang]/_utils/dictionary/developers.ts` under `DEVELOPERS_DICT.page`, **except** WhyShapeShift, WidgetSection's feature ring, ApiSection's code panels, EconomicsSection's milestones, and LaunchPath's Q&A, which hardcode their copy directly in JSX (illustration- or interaction-heavy sections where copy, visuals, and behavior are tightly coupled).
-- `DevelopersHero.tsx` embeds the real `@shapeshiftoss/swap-widget` React SDK (dynamically imported, `ssr: false`) only when `NEXT_PUBLIC_ENABLE_DEVELOPERS_SWAP_WIDGET=true`. The embed failed QA, so this flag stays off for the current release; set it to `true` and rebuild after the follow-up fix. When enabled, it needs `NEXT_PUBLIC_WALLETCONNECT_PROJECT_ID`. Set this public Reown project ID before building (Next.js embeds it in the client bundle); the existing swap-widget service uses the value documented in `.env.local.sample`. Configure it in each Railway environment before promoting this page. Verify the website origin is allowed in Reown and test wallet connection before release. Set `NEXT_PUBLIC_SHAPESHIFT_PARTNER_CODE` to ShapeShift's registered affiliate code before release so website swaps are attributed to its payout account; verify the code via `/v1/partner/{code}`.
+- `DevelopersHero.tsx` embeds the real `@shapeshiftoss/swap-widget` React SDK (dynamically imported, `ssr: false`) only when `NEXT_PUBLIC_ENABLE_DEVELOPERS_SWAP_WIDGET=true`. The embed failed QA, so this flag stays off for the current release; set it to `true` and rebuild after the follow-up fix. When enabled, it needs `NEXT_PUBLIC_WALLETCONNECT_PROJECT_ID`. Set this public Reown project ID before building (Next.js embeds it in the client bundle); the existing swap-widget service uses the value documented in `.env.local.sample`. Configure it in each Railway environment before promoting this page. Set `NEXT_PUBLIC_SHAPESHIFT_PARTNER_CODE` to ShapeShift's registered affiliate code before release so website swaps are attributed to its payout account; verify the code via `/v1/partner/{code}`.
+- **Reown allowed origins (required for WalletConnect).** The Reown project behind `NEXT_PUBLIC_WALLETCONNECT_PROJECT_ID` has a domain allowlist, enforced server-side by the WalletConnect relay. An origin that isn't listed gets its relay socket closed with `3000 Unauthorized: origin not allowed`, so the WalletConnect QR renders blank and mobile wallet pairing never starts. Injected wallets (Rabby, MetaMask, Phantom) are unaffected, which is why everything else on the page looks fine. Before enabling the embed in any environment, add that environment's exact origin (e.g. `https://shapeshift.com`, `https://website-frontend-develop.up.railway.app`, any PR preview URL) under the project's allowed domains at <https://dashboard.reown.com>. Check the current list with `curl "https://api.web3modal.org/projects/v1/origins?projectId=<id>&st=appkit&sv=html-wagmi-1" -H "x-project-id: <id>" -H "x-sdk-type: appkit" -H "x-sdk-version: html-wagmi-1"`. At the time of writing only the `*-widget.shapeshift.com` demo hosts are listed.
+- `DevelopersSwapWidget.tsx` initialises AppKit itself (`_utils/initDevelopersAppKit.ts`) rather than letting the widget do it, so the page can supply chain icons AppKit lacks presets for and route RPC reads through ShapeShift's proxies. Its network/adapter list mirrors the widget's own `config/appkit.ts`; keep them in step when bumping `@shapeshiftoss/swap-widget`.
 - Client components (interactive state, refs, or the widget's own client-only requirements): `DevelopersHero`, `DevelopersWidgetSection`, `DevelopersApiSection`, `DevelopersFaq`, `DevelopersPartnerLogos`. Everything else is a server component.
 - Reuses existing shared components (`Button`, `LocalizedLink`) and Tailwind color tokens from `tailwind.config.ts`.