Initiële commit: VibeFinance 3-container opzet

Basislijn van de bestaande applicatie (Vite/React frontend, Express
backend, PostgreSQL) zoals die in de index stond, plus dev-, release-
en documentatiescripts.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/main.jsx

@@ -0,0 +1,9 @@
+import { StrictMode } from "react";
+import { createRoot } from "react-dom/client";
+import App from "./App.jsx";
+
+createRoot(document.getElementById("root")).render(
+  <StrictMode>
+    <App />
+  </StrictMode>
+);