Prepare Airship frontend for ChatGPT Sites portability test

.env.example

@@ -0,0 +1,5 @@
+VITE_AIRSHIP_API_BASE=https://game.arrowstack.dev
+VITE_AIRSHIP_WS_BASE=wss://game.arrowstack.dev
+VITE_KEYCLOAK_URL=https://auth.arrowstack.dev
+VITE_KEYCLOAK_REALM=dev
+VITE_KEYCLOAK_CLIENT_ID=airship-web

SITES.md

@@ -0,0 +1,27 @@
+# ChatGPT Sites portability test
+
+This branch keeps ChatGPT Sites at the presentation boundary only.
+
+## Ownership boundary
+
+- Sites: built Phaser/Vite frontend and static assets.
+- Arrowstack: Keycloak identity, API, authoritative multiplayer simulation, PostgreSQL state, and WebSocket transport.
+
+The browser defaults still point to:
+
+- API: https://game.arrowstack.dev
+- WebSocket: wss://game.arrowstack.dev
+- Identity: https://auth.arrowstack.dev, realm `dev`, client `airship-web`
+
+They can be overridden with the Vite variables in `.env.example`.
+
+## First deployment
+
+Ask Sites to build this existing Vite project without moving the Go server or game state into Sites.
+
+Once Sites returns its production origin, add that exact HTTPS origin to:
+
+1. the Airship Go server `ALLOWED_ORIGINS` value, and
+2. the Keycloak `airship-web` client's redirect URIs and web origins.
+
+Until those origin allow-lists are updated, the game should still render and remain usable in solo mode; authenticated multiplayer is expected to fail closed.

src/multiplayer.js

@@ -1,11 +1,12 @@
 import Keycloak from 'keycloak-js';
 
-const API_BASE = 'https://game.arrowstack.dev';
+const env = import.meta.env || {};
-const WS_BASE = 'wss://game.arrowstack.dev';
+const API_BASE = env.VITE_AIRSHIP_API_BASE || 'https://game.arrowstack.dev';
+const WS_BASE = env.VITE_AIRSHIP_WS_BASE || 'wss://game.arrowstack.dev';
 const KEYCLOAK_CONFIG = {
-  url: 'https://auth.arrowstack.dev',
+  url: env.VITE_KEYCLOAK_URL || 'https://auth.arrowstack.dev',
-  realm: 'dev',
+  realm: env.VITE_KEYCLOAK_REALM || 'dev',
-  clientId: 'airship-web',
+  clientId: env.VITE_KEYCLOAK_CLIENT_ID || 'airship-web',
 };
 
 const clamp = (value, min, max) => Math.max(min, Math.min(max, value));