Add RollkofferSimulator iOS SpriteKit arcade game

Complete implementation of a 2D top-down arcade collector game where players
control a rolling suitcase through an airport, collecting good dogs and green
people while avoiding bad dogs and gray people.

Features:
- Touch & drag controls for suitcase movement
- Automatic scrolling airport floor with tile pattern
- 4 entity types: good dogs (small/big), bad dogs, green/gray humans
- Spawn system with configurable distribution rates
- Collision detection with visual feedback effects
- Score tracking with high score persistence
- 90-second time limit with 10 dogs + 5 humans goal
- 3 lives system with invincibility frames
- Menu, Game, GameOver, and Victory scenes
- German UI text (Created by Ingo K.)

Technical:
- iOS 15+ with SpriteKit framework
- Modular architecture with Nodes, Managers, Scenes
- Physics-based collision detection
- UserDefaults for score persistence

RollkofferSimulator/Assets.xcassets/AccentColor.colorset/Contents.json

@@ -0,0 +1,20 @@
+{
+  "colors" : [
+    {
+      "color" : {
+        "color-space" : "srgb",
+        "components" : {
+          "alpha" : "1.000",
+          "blue" : "0.600",
+          "green" : "0.300",
+          "red" : "0.400"
+        }
+      },
+      "idiom" : "universal"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

RollkofferSimulator/Assets.xcassets/AppIcon.appiconset/Contents.json

@@ -0,0 +1,13 @@
+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "platform" : "ios",
+      "size" : "1024x1024"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

RollkofferSimulator/Assets.xcassets/Contents.json

@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}