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/NetworkBootstrap.cs

@@ -0,0 +1,69 @@
+using Unity.Netcode;
+using UnityEngine;
+#if ENABLE_INPUT_SYSTEM
+using UnityEngine.InputSystem;
+#endif
+
+/// <summary>
+/// Dev-only connection harness for local multiplayer testing across the junction-mirror clones:
+/// one instance clicks Host, the others click Client (loopback 127.0.0.1 via the configured
+/// UnityTransport). Draws a small on-screen panel and exposes hotkeys (H = Host, C = Client,
+/// J = Server, K = Shutdown). Purely a testing scaffold — replace with real lobby/menu UI later.
+/// Attach to the same GameObject as the NetworkManager.
+/// </summary>
+[RequireComponent(typeof(NetworkManager))]
+[DisallowMultipleComponent]
+public class NetworkBootstrap : MonoBehaviour
+{
+    [Tooltip("Draw the on-screen Host/Client panel (top-left).")]
+    public bool showGui = true;
+
+    [Tooltip("Allow the H/C/J/K keyboard shortcuts.")]
+    public bool enableHotkeys = true;
+
+    private NetworkManager _net;
+
+    private void Awake() => _net = GetComponent<NetworkManager>();
+
+    private void Update()
+    {
+        if (!enableHotkeys) return;
+#if ENABLE_INPUT_SYSTEM
+        var kb = Keyboard.current;
+        if (kb == null || _net == null) return;
+        if (!_net.IsListening)
+        {
+            if (kb.hKey.wasPressedThisFrame) _net.StartHost();
+            else if (kb.cKey.wasPressedThisFrame) _net.StartClient();
+            else if (kb.jKey.wasPressedThisFrame) _net.StartServer();
+        }
+        else if (kb.kKey.wasPressedThisFrame)
+        {
+            _net.Shutdown();
+        }
+#endif
+    }
+
+    private void OnGUI()
+    {
+        if (!showGui || _net == null) return;
+
+        GUILayout.BeginArea(new Rect(10, 10, 220, 160), GUI.skin.box);
+        if (!_net.IsListening)
+        {
+            GUILayout.Label("Netcode (dev)");
+            if (GUILayout.Button("Host (H)")) _net.StartHost();
+            if (GUILayout.Button("Client (C)")) _net.StartClient();
+            if (GUILayout.Button("Server (J)")) _net.StartServer();
+        }
+        else
+        {
+            string role = _net.IsHost ? "Host" : _net.IsServer ? "Server" : "Client";
+            GUILayout.Label($"Role: {role}");
+            GUILayout.Label($"ClientId: {_net.LocalClientId}");
+            GUILayout.Label($"Clients: {(_net.IsServer ? _net.ConnectedClients.Count : (_net.IsConnectedClient ? 1 : 0))}");
+            if (GUILayout.Button("Shutdown (K)")) _net.Shutdown();
+        }
+        GUILayout.EndArea();
+    }
+}