M1: add NGO + Multiplayer Services packages and prototype scripts (compiling)

Netcode for GameObjects 2.13.0 + Unity Multiplayer Services 2.2.4 (unified
Relay/Lobby SDK; supersedes deprecated standalone relay/lobby). Four M1
scripts, verified against live editor reflection and compiling clean:
- Net/NetworkBootstrap.cs  Relay host/join-by-code harness (IMGUI)
- Net/PlayerDriver.cs       replicated host-auth capsule (input->ServerRpc->host)
- Bot/TreadPart.cs          v0.1 tread feel: snap-to-cruise/lock-pivot/lean
- Bot/SeatManager.cs        left/right tread seat claim + leaver-safety

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Packages/manifest.json

@@ -7,7 +7,9 @@
     "com.unity.ide.visualstudio": "2.0.26",
     "com.unity.inputsystem": "1.19.0",
     "com.unity.multiplayer.center": "1.0.1",
+    "com.unity.netcode.gameobjects": "2.13.0",
     "com.unity.render-pipelines.universal": "17.5.0",
+    "com.unity.services.multiplayer": "2.2.4",
     "com.unity.test-framework": "1.7.0",
     "com.unity.timeline": "1.8.12",
     "com.unity.ugui": "2.5.0",