add empty chat endpoint

apps/chat/env.d.ts

@@ -0,0 +1,12 @@
+// oxlint-disable @typescript-eslint/consistent-type-imports
+type LocalEnv = import('./src/context').Env
+type MainModule = typeof import('./src/chat.app')
+
+// Add Env to Cloudflare namespace so that we can access it via
+// import { env } from 'cloudflare:workers'
+declare namespace Cloudflare {
+	interface Env extends LocalEnv {}
+	interface GlobalProps {
+		mainModule: MainModule
+	}
+}