Enhance new game modal with running game state handling

Introduced functionality to detect and handle ongoing games in the new game modal. The modal now switches between "running" and "choice" modes based on game state, improving clarity for users. Added a dedicated section to display the game code when a game is active.

frontend/src/App.jsx

@@ -263,6 +263,15 @@ export default function App() {
 
   // ===== New game flow =====
   const createGame = async () => {
+    // ✅ wichtig: alten Game-State weg, damit nix "hängen" bleibt
+    setSheet(null);
+    setGameMeta(null);
+    setMembers([]);
+    setWinnerUserId("");
+    setPulseId(null);
+    setChipOpen(false);
+    setChipEntry(null);
+
     const g = await api("/games", {
       method: "POST",
       body: JSON.stringify({ name: "Spiel " + new Date().toLocaleString() }),
@@ -270,9 +279,10 @@ export default function App() {
 
     const gs = await api("/games");
     setGames(gs);
+
+    // ✅ auf neues Spiel wechseln (triggered dann reloadSheet/loadGameMeta via effect)
     setGameId(g.id);
 
-    // meta/members will load via gameId effect
     return g; // includes code
   };
 
@@ -503,6 +513,9 @@ export default function App() {
         onClose={() => setNewGameOpen(false)}
         onCreate={createGame}
         onJoin={joinGame}
+        currentCode={gameMeta?.code || ""}
+        gameFinished={!!gameMeta?.winner_user_id}
+        hasGame={!!gameId}
       />
 
       <ChipModal