Passenger/driver sit still in moving cars: seat pose sent relative to the vehicle (backward-compatible), no backward pull; remote cars/traffic extrapolate in physics time and interpolate; UI polish (shadows, borders, gradient buttons, server list hover, fill bars, colored ping)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Passenger.cs

@@ -29,6 +29,10 @@ namespace MSCO
         readonly List<Rigidbody> frozenBodies = new List<Rigidbody>();
 
         public bool IsRiding { get { return vehicle != null; } }
+        /// <summary>Fahrzeug, in dem wir mitfahren (sonst null).</summary>
+        public SyncedBody Vehicle { get { return vehicle; } }
+        /// <summary>Kopf auf dem Sitz, relativ zum Fahrzeug (genau, nicht aus der Weltposition des letzten Frames).</summary>
+        public Vector3 SeatHeadLocal { get { return seatHeadLocal; } }
 
         /// <summary>Taste gedrückt: einsteigen oder aussteigen. Gibt einen Statustext zurück.</summary>
         public string Toggle(Transform player, Camera cam, ObjectSync objects, IDictionary<int, PlayerInfo> players)