Frontend menu + settings + saves foundation

Netcode frontend pattern: UITK main menu / pause / settings (MenuUi + controllers), on-demand world lifecycle (WorldLauncher/SessionRunner), GameBootstrap menu branch; Graphics/Audio settings (SettingsService/GameVolume); single-slot save foundation (SaveData/SaveService, born-correct load at director spawn, autosave on Siege->Calm + quit); RuntimePanelSettings + theme; BuildTool menu; 10 EditMode tests.

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

Assets/_Project/Scripts/Simulation/GameBootstrap.cs

@@ -10,7 +10,7 @@ namespace ProjectM.Simulation
     /// <para>
     /// M4 (LAN co-op): auto-connect is DISABLED (<see cref="ClientServerBootstrap.AutoConnectPort"/> = 0).
     /// Listening/connecting is driven explicitly via the <see cref="ConnectionConfig"/> singleton and the
-    /// per-world ConnectionControlSystems — from <c>ConnectionUI</c> (Host / Join + IP) in player builds,
+    /// per-world ConnectionControlSystems — from the UITK frontend menu (<c>MainMenuController</c> → <c>WorldLauncher</c>, Host / Join + IP) in player builds,
     /// or from the editor-only <c>EditorAutoHostSystem</c>, which auto-hosts on loopback and connects the
     /// in-proc client plus any Multiplayer-PlayMode-Tools thin clients. Direct IP/LAN only for now; Unity
     /// Relay is deferred to a later pass.
@@ -21,10 +21,34 @@ namespace ProjectM.Simulation
     {
         public override bool Initialize(string defaultWorldName)
         {
-            // No auto-connect: ConnectionConfig + the ConnectionControlSystems own listen/connect (M4).
+            // No auto-connect: the menu (or, in the editor, the auto-host system) owns listen/connect.
             AutoConnectPort = 0;
-            CreateDefaultClientServerWorlds();
-            return true;
+
+#if UNITY_EDITOR
+            // Editor: keep today's instant-into-game + MPPM loop by DEFAULT. Only the MAIN editor
+            // (ClientAndServer) with the "Boot Into Menu (Editor)" toggle ON takes the frontend path, so MPPM
+            // virtual players (Client) never boot to the menu. Open MainMenu.unity + Play to test the menu.
+            bool bootMenu = UnityEditor.EditorPrefs.GetBool("ProjectM.BootIntoMenu", false)
+                            && RequestedPlayType == PlayType.ClientAndServer;
+            if (!bootMenu)
+            {
+                CreateDefaultClientServerWorlds();
+                return true;
+            }
+            return false; // Frontend: Entities makes a single default "menu" world; MainMenuController drives sessions.
+#else
+            // Player build: a dedicated/headless server auto-hosts; everyone else boots the front-end menu.
+            if (RequestedPlayType == PlayType.Server)
+            {
+                var server = CreateServerWorld("ServerWorld");
+                World.DefaultGameObjectInjectionWorld = server;
+                var em = server.EntityManager;
+                var e = em.CreateEntity();
+                em.AddComponentData(e, new ConnectionConfig { Mode = ConnectionMode.Host, Address = "0.0.0.0", Port = 7979, Requested = true });
+                return true;
+            }
+            return false; // Frontend menu (MainMenu.unity is build index 0).
+#endif
         }
     }
 }