docs(website): Node 22.23.4 floor in the README mirror (Node2Shell)

Mirrors website#226: the images move off end-of-life Node 20 to
node:22.23.4-alpine, the first 22.x with the CVE-2026-111497 Brotli fix.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

website/website-README.md

@@ -147,7 +147,7 @@ flowchart TB
 
 | Layer | Tech |
 |---|---|
-| Backend | Node.js 20+, Express 4, `mariadb` driver (parameterized SQL, no ORM) |
+| Backend | Node.js 22 (images pin 22.23.4), Express 4, `mariadb` driver (parameterized SQL, no ORM) |
 | Auth | Session service over JWT: httpOnly cookie (web) + bearer access/refresh tokens (mobile), bcrypt hashing, optional TOTP 2FA (`speakeasy` + `qrcode`), pluggable OAuth2/OIDC SSO (built-in Google & Discord + generic) |
 | Database | MariaDB 11 (own container) |
 | Frontend | React 18, Vite 5, React Router 6 |
@@ -196,7 +196,8 @@ website/
 
 ## Prerequisites
 
-- **Node.js 20+** and npm (Node 22/24 are fine).
+- **Node.js 22.23.4+** (or 24.22.1+) and npm. Older builds carry the Node2Shell Brotli bug
+  (CVE-2026-111497), and Node 20 is past end of life.
 - **Docker Desktop** (for MariaDB, and for the full Compose deploy).
 
 ---