Enhance project setup with Prisma, new scripts, and dependencies; update README for clarity and add API routes; improve layout and styling for better user experience

src/components/ThemeToggle.tsx

@@ -0,0 +1,18 @@
+"use client";
+
+import { useTheme } from "./ThemeProvider";
+
+export function ThemeToggle() {
+  const { theme, setTheme } = useTheme();
+
+  return (
+    <button
+      type="button"
+      onClick={() => setTheme(theme === "dark" ? "light" : "dark")}
+      className="font-mono text-xs text-zinc-600 dark:text-zinc-500 hover:text-zinc-800 dark:hover:text-zinc-300 transition-colors"
+      title={theme === "dark" ? "Passer au thème clair" : "Passer au thème sombre"}
+    >
+      {theme === "dark" ? "☀" : "☽"}
+    </button>
+  );
+}