docs(website-adr): record website CI as implemented (ADR-website-001 §4)

The Gitea Actions → Cloudflare Pages pipeline shipped; update §4 from
"No CI yet" to the implemented workflow, the `relplay` project, the
branch→environment mapping, and the required secrets.

docs/website/adr/20260604-adr-website-001.md

@@ -82,9 +82,16 @@ planning + `/runda` pass with the user and are recorded below.
    assets)** over Pages; either serves the static `dist/` and needs no Astro
    adapter (the `@astrojs/cloudflare` adapter is only for SSR, which the site
    does not use). The future in-page WASM playground (§3), if it needs
-   COOP/COEP headers, can get them from Cloudflare `_headers`. **No CI yet** —
+   COOP/COEP headers, can get them from Cloudflare `_headers`. **CI implemented
-   the site is tested locally (`pnpm dev` / `pnpm build`) until the repo reaches
+   2026-06-15** (`.gitea/workflows/website.yaml`): a push touching `website/**`
-   its public home, when the Gitea Actions workflow lands.
+   builds the static site with pnpm and deploys `dist/` to the Cloudflare Pages
+   project **`relplay`** via `wrangler` (Direct Upload — no Git integration).
+   The `--branch` label selects environment against the project's production
+   branch (`main`): **`main` → production (`relplay.org`)**, **`website` →
+   preview (`website.relplay.pages.dev`)**, with `staging.relplay.org` attachable
+   to the `website` branch alias. The crate's CI gate (`ci.yaml`) skips
+   website-only pushes; the build is pure-Node (the `.cast` files are committed,
+   so no cargo). Secrets: `CLOUDFLARE_API_TOKEN` + `CLOUDFLARE_ACCOUNT_ID`.
 
 5. **Repo topology — monorepo.** The site lives under `website/` in the
    playground repo; the crate stays at the repo root. The repo as a whole