feat: bootstrap Vite and pnpm toolchain contract

src/bootstrap/main.jsx

@@ -0,0 +1,23 @@
+import { StrictMode } from "react";
+import { createRoot } from "react-dom/client";
+
+function BootstrapShell() {
+  return (
+    <main>
+      <h1>Clean Architecture Frontend</h1>
+      <p>런타임 계약을 불러오는 중입니다.</p>
+    </main>
+  );
+}
+
+const rootElement = document.getElementById("root");
+
+if (!rootElement) {
+  throw new Error("Missing #root mount element");
+}
+
+createRoot(rootElement).render(
+  <StrictMode>
+    <BootstrapShell />
+  </StrictMode>,
+);