Major pipeline changes to map building, introducing 3player map, and adding Shared build mode to level authoring options

Assets/_Project/Levels/LevelAuthoring.cs

@@ -51,6 +51,16 @@ namespace TD.Levels
         [Tooltip("Optional author/credit text. Empty triggers a soft warning at bake time.")]
         public string author = "";
 
+        [Header("Rules")]
+        [Tooltip("OwnerOnly: players can only build inside their own PlayerZoneVolume — the classic " +
+                 "one-maze-each layout.\n\n" +
+                 "Shared: any player can build on any Buildable tile, so the whole map is one " +
+                 "cooperative maze. Zones still define territory for leak attribution, camera " +
+                 "start, builder spawn and minimap tinting — only the build restriction lifts.\n\n" +
+                 "Towers always belong to whoever paid for them; sell and upgrade stay owner-gated " +
+                 "under both modes.")]
+        public BuildAccess buildAccess = BuildAccess.OwnerOnly;
+
         // -------------------------------------------------------------------
         // Gizmo visibility toggles. Each volume type reads its own toggle to decide whether to
         // draw always-on or only-when-selected.