Add PlayerCode for enhanced score tracking and host validation logic in cooperative mode. Optimize UI for mobile devices with new responsive styles.

pkg/server/room.go

@@ -70,6 +70,7 @@ type Room struct {
 	Countdown         int
 	NextStart         time.Time
 	HostID            string
+	HostPlayerCode    string          // PlayerCode des Hosts (für Coop-Score Submission)
 	TeamName          string          // Name des Teams (vom Host gesetzt)
 	CollectedCoins    map[string]bool // Key: "chunkID_objectIndex"
 	CollectedPowerups map[string]bool // Key: "chunkID_objectIndex"
@@ -790,6 +791,7 @@ func (r *Room) Broadcast() {
 		TimeLeft:          r.Countdown,
 		WorldChunks:       r.ActiveChunks,
 		HostID:            r.HostID,
+		HostPlayerCode:    r.HostPlayerCode,
 		TeamName:          r.TeamName,
 		ScrollX:           r.GlobalScrollX,
 		CollectedCoins:    r.CollectedCoins,