Add staging env

src/env.native.ts

@@ -1,8 +1,13 @@
 // @ts-ignore types not available -prf
-import {REACT_APP_AUTH_LOBBY} from '@env'
+import {REACT_APP_BUILD} from '@env'
 
-if (typeof REACT_APP_AUTH_LOBBY !== 'string') {
-  throw new Error('ENV: No auth lobby provided')
+if (typeof REACT_APP_BUILD !== 'string') {
+  throw new Error('ENV: No env provided')
+}
+if (!['dev', 'staging', 'prod'].includes(REACT_APP_BUILD)) {
+  throw new Error(
+    `ENV: Env must be "dev", "staging", or "prod," got "${REACT_APP_BUILD}"`,
+  )
 }
 
-export const AUTH_LOBBY = REACT_APP_AUTH_LOBBY
+export const BUILD = REACT_APP_BUILD