Fix Turbopack build: avoid cross-boundary import in EnvironmentContext

Read sessionStorage directly instead of importing getCurrentEnvironment
from api.ts to avoid Turbopack module boundary resolution error.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

admin-ui/src/lib/EnvironmentContext.tsx

@@ -1,7 +1,13 @@
 "use client";
 
 import { createContext, useContext, useState, useEffect, type ReactNode } from "react";
-import { getCurrentEnvironment, setCurrentEnvironment } from "@/lib/api";
+import { setCurrentEnvironment } from "@/lib/api";
+
+const ENVIRONMENT_STORAGE_KEY = "rustycms_admin_environment";
+function readStoredEnvironment(): string | null {
+  if (typeof window === "undefined") return null;
+  return sessionStorage.getItem(ENVIRONMENT_STORAGE_KEY);
+}
 
 type EnvironmentContextType = {
   environment: string | null;
@@ -17,7 +23,7 @@ export function EnvironmentProvider({ children }: { children: ReactNode }) {
   const [environment, setEnv] = useState<string | null>(null);
 
   useEffect(() => {
-    setEnv(getCurrentEnvironment());
+    setEnv(readStoredEnvironment());
   }, []);
 
   function setEnvironment(env: string) {