feat: initial elysium idle game prototype

Sets up the full monorepo with pnpm workspaces. Includes shared types
package, Hono API with Discord OAuth/JWT auth, Prisma v6 + MongoDB
Atlas, and React + Vite frontend with game loop, five tabs, and
Discord-linked save/load.

apps/web/src/components/game/OfflineModal.tsx

@@ -0,0 +1,27 @@
+import { useGame } from "../../context/GameContext.js";
+
+export const OfflineModal = (): React.JSX.Element | null => {
+  const { offlineGold, dismissOfflineGold } = useGame();
+
+  if (offlineGold <= 0) return null;
+
+  return (
+    <div className="modal-overlay">
+      <div className="modal">
+        <h2>Welcome back!</h2>
+        <p>
+          Your adventurers kept working whilst you were away and earned{" "}
+          <strong>🪙 {offlineGold.toFixed(0)} gold</strong>!
+        </p>
+        <p className="modal-note">Offline progress is calculated up to 8 hours.</p>
+        <button
+          className="modal-close-button"
+          onClick={dismissOfflineGold}
+          type="button"
+        >
+          Collect!
+        </button>
+      </div>
+    </div>
+  );
+};