map follow on drone focus. rubberband pointing to next waypoint. drone icon bigger 40px

app/lib/ui/widgets/nav_icon_button.dart

@@ -4,11 +4,20 @@ import 'package:flutter/material.dart';
 /// Plan- (MapSearchControls: Home/Fit) und Fly-Modus-Kartensteuerungen
 /// (FlyMapControls: Drohne/Fit).
 class NavIconButton extends StatelessWidget {
-  const NavIconButton({super.key, required this.icon, required this.onTap});
+  const NavIconButton({
+    super.key,
+    required this.icon,
+    required this.onTap,
+    this.active = false,
+  });
 
   final IconData icon;
   final VoidCallback onTap;
 
+  /// Rosa Akzentrand (Doku 3.10: DroneMarkerIcon-Farbe) fuer Knoepfe mit
+  /// an/aus-Zustand, z.B. den Drohnen-Folgemodus (FlyMapControls).
+  final bool active;
+
   @override
   Widget build(BuildContext context) {
     return GestureDetector(
@@ -19,6 +28,9 @@ class NavIconButton extends StatelessWidget {
         decoration: BoxDecoration(
           shape: BoxShape.circle,
           color: Colors.black.withValues(alpha: 0.55),
+          border: active
+              ? Border.all(color: const Color(0xFFFF2E93), width: 2)
+              : null,
         ),
         child: Icon(icon, color: Colors.white, size: 16),
       ),