Initial commit: StackPilot Phase 1 (Core)

Self-hosted Docker Compose manager.
- Backend: FastAPI + docker-py + SQLite (JWT auth, file-first stacks,
  lifecycle, live status, WebSocket logs, docker-run converter, audit log)
- Frontend: React + Vite + Tailwind (login/setup, dashboard, stacks,
  stack detail, Monaco editor, dark/light theme)
- Deployment: docker-compose.yml, Dockerfiles, nginx reverse proxy

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/main.tsx

@@ -0,0 +1,19 @@
+import React from "react";
+import ReactDOM from "react-dom/client";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+import { Toaster } from "sonner";
+import App from "./App";
+import "./index.css";
+
+const queryClient = new QueryClient({
+  defaultOptions: { queries: { retry: 1, refetchOnWindowFocus: false } },
+});
+
+ReactDOM.createRoot(document.getElementById("root")!).render(
+  <React.StrictMode>
+    <QueryClientProvider client={queryClient}>
+      <App />
+      <Toaster position="top-right" richColors theme="system" />
+    </QueryClientProvider>
+  </React.StrictMode>
+);