chore: add project scaffolding, third-party assets and settings

- Terrain, Prefabs, Textures, Modelle (u. a. Lieferkarton-/Vibrations-
  Rohdaten in Assets/Data)
- Third-Party-Pakete: TextMesh Pro, Toby Fredson Foliage Engine, Sat
  Productions Street Lights, ProBuilder Data
- Neue Szene Boot.unity, Shop-Szenenordner
- Package-Manifest/Lock, ProjectSettings, Build-Profile, .slnx
- Doku: EDITOR_SETUP.md, INSTALL.md, TODO.md

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Packages/manifest.json

@@ -1,13 +1,18 @@
 {
   "dependencies": {
+    "com.unity.ai.assistant": "2.17.0-pre.1",
+    "com.unity.ai.inference": "2.6.1",
     "com.unity.ai.navigation": "2.0.14",
     "com.unity.collab-proxy": "2.13.5",
-    "com.unity.ide.rider": "3.0.38",
+    "com.unity.ide.rider": "3.0.40",
     "com.unity.ide.visualstudio": "2.0.26",
     "com.unity.inputsystem": "1.20.0",
     "com.unity.multiplayer.center": "1.0.1",
     "com.unity.netcode.gameobjects": "2.13.1",
+    "com.unity.probuilder": "6.1.2",
+    "com.unity.progrids": "3.0.3-preview.6",
     "com.unity.render-pipelines.universal": "17.5.0",
+    "com.unity.terrain-tools": "5.3.2",
     "com.unity.test-framework": "1.7.0",
     "com.unity.timeline": "1.8.12",
     "com.unity.ugui": "2.5.0",