feat: add user accounts, authentication, and game history with Prisma 7

- Implement user registration and login with NextAuth v5 (email/password, JWT)
- Add authentication modal in UI with login/register tabs
- Create user profile screen showing game statistics and history
- Integrate Prisma 7 ORM with SQLite database for data persistence
- Store game results (mode, path, clicks, time) in database
- Auto-save completed games only when user is authenticated
- Separate business logic into reusable hooks (useSoloGame, useMultiGame)
- Organize UI into composable screen components (HomeScreen, SoloScreen, ProfileScreen, etc)
- Add session persistence across F5 refresh for solo and multiplayer
- Style auth modal, account button, and profile stats dashboard

app/components/Breadcrumbs.tsx

@@ -0,0 +1,24 @@
+"use client";
+
+import { useRef } from "react";
+
+export function Breadcrumbs({ history, endRef }: { history: string[]; endRef: React.RefObject<HTMLDivElement | null> }) {
+  return (
+    <div className="breadcrumb-trail">
+      {history.map((title, i) => (
+        <span key={i} className="breadcrumb-item">
+          {i > 0 && <span className="breadcrumb-sep">›</span>}
+          <span className={i === history.length - 1 ? "breadcrumb-current" : "breadcrumb-past"}>
+            {title}
+          </span>
+        </span>
+      ))}
+      <div ref={endRef} />
+    </div>
+  );
+}
+
+export function useBreadcrumbScroll() {
+  const endRef = useRef<HTMLDivElement>(null);
+  return endRef;
+}