feat: validate runtime configuration before mount

src/bootstrap/main.jsx

@@ -1,11 +1,24 @@
 import { StrictMode } from "react";
 import { createRoot } from "react-dom/client";
 
-function BootstrapShell() {
+import { BootConfigError, loadRuntimeConfig } from "./load-runtime-config.js";
+
+/** @param {{ environment: string }} props */
+function BootstrapShell({ environment }) {
   return (
     <main>
       <h1>Clean Architecture Frontend</h1>
-      <p>런타임 계약을 불러오는 중입니다.</p>
+      <p>{environment} 런타임 계약이 검증되었습니다.</p>
+    </main>
+  );
+}
+
+/** @param {{ supportReference: string }} props */
+function BootErrorShell({ supportReference }) {
+  return (
+    <main role="alert">
+      <h1>애플리케이션을 시작할 수 없습니다.</h1>
+      <p>지원 참조: {supportReference}</p>
     </main>
   );
 }
@@ -16,8 +29,24 @@ if (!rootElement) {
   throw new Error("Missing #root mount element");
 }
 
-createRoot(rootElement).render(
-  <StrictMode>
-    <BootstrapShell />
-  </StrictMode>,
-);
+const root = createRoot(rootElement);
+
+async function boot() {
+  try {
+    const runtime = await loadRuntimeConfig();
+    root.render(
+      <StrictMode>
+        <BootstrapShell environment={runtime.config.APP_ENV} />
+      </StrictMode>,
+    );
+  } catch (error) {
+    const supportReference =
+      error instanceof BootConfigError
+        ? error.safe.supportReference
+        : "boot:unknown";
+
+    root.render(<BootErrorShell supportReference={supportReference} />);
+  }
+}
+
+void boot();