Add NGO networking with owner-authoritative player position sync

Install Netcode for GameObjects 2.13.0 + Unity Transport 2.6.0 and wire up
the first networking milestone: syncing player position/rotation across clients.

- NetworkBootstrap: Host/Client/Server controls (OnGUI + H/C hotkeys) for
  local clone testing over loopback 127.0.0.1:7777.
- NetworkPlayerSetup: per-avatar owner gating. The local owner binds the
  GameModeManager and cameras to itself; remote avatars disable their
  controller/CharacterController and receive transform via NetworkTransform.
- GameModeManager.BindLocalPlayer: central runtime rebind to the locally
  spawned player.
- FirstPersonController.SetPlayer: explicit runtime rebind hook.
- Player prefab: NetworkObject + NetworkTransform (owner-authoritative,
  position + rotation) + NetworkPlayerSetup; registered as PlayerPrefab.
- Scene: NetworkManager + UnityTransport added; the fixed scene player
  instance removed in favor of spawn-on-connect.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/Scripts/NetworkPlayerSetup.cs

@@ -0,0 +1,32 @@
+using Unity.Netcode;
+using UnityEngine;
+
+/// <summary>
+/// Per-avatar network glue on the spawned player. The local owner binds the scene singletons
+/// (GameModeManager, cameras) to itself via <see cref="GameModeManager.BindLocalPlayer"/>; remote
+/// avatars stop simulating so their transform is driven purely by the NetworkTransform replication.
+/// Position-sync milestone: remote avatars still show their mesh/idle pose, just no local control.
+/// </summary>
+[RequireComponent(typeof(PlayerCharacterController))]
+[DisallowMultipleComponent]
+public class NetworkPlayerSetup : NetworkBehaviour
+{
+    public override void OnNetworkSpawn()
+    {
+        var controller = GetComponent<PlayerCharacterController>();
+
+        if (IsOwner)
+        {
+            var manager = FindFirstObjectByType<GameModeManager>(FindObjectsInactive.Include);
+            if (manager)
+                manager.BindLocalPlayer(controller);
+            return;
+        }
+
+        // Remote avatar: NetworkTransform owns the transform here, so disable the local
+        // simulation (input/movement) and the CharacterController's own depenetration.
+        if (controller) controller.enabled = false;
+        var cc = GetComponent<CharacterController>();
+        if (cc) cc.enabled = false;
+    }
+}