LANTERN purge B1: delete the automation chain (Harvester/Conveyor/Fabricator)

Deletes the M7 production systems, automation components/math, authoring, 3
machine prefabs, and 6 test files (-43 tests, 459 green). Trims the automation
paths out of BaseRestoreSystem/SaveStructureScan/BuildPlaceSystem/BuildSendSystem/
HudSystem/HudTheme/StructureCatalogAuthoring/Tuning. RuntimePlacedTag (save
marker, a keeper) re-homed into StructureComponents.cs. StructureType byte codes
stay reserved.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Assets/_Project/Scripts/Client/UI/HudTheme.cs

@@ -51,14 +51,10 @@ namespace ProjectM.Client
         public Sprite TurretIcon;
         public Sprite WallIcon;
         public Sprite PylonIcon;
-        public Sprite HarvesterIcon;
-        public Sprite FabricatorIcon;
-        public Sprite ConveyorIcon;
 
         [Header("Build-ghost preview meshes (authored real-size, ground pivot — BuildSendSystem)")]
         public Mesh TurretGhostMesh;
         public Mesh WallGhostMesh;
-        public Mesh FabricatorGhostMesh;
 
         [Header("Build-mode control glyphs")]
         public Sprite KbmPlace;     // LMB
@@ -89,9 +85,6 @@ namespace ProjectM.Client
                 case StructureType.Turret: return TurretIcon;
                 case StructureType.Wall: return WallIcon;
                 case StructureType.Pylon: return PylonIcon;
-                case StructureType.Harvester: return HarvesterIcon;
-                case StructureType.Fabricator: return FabricatorIcon;
-                case StructureType.Conveyor: return ConveyorIcon;
                 default: return null;
             }
         }
@@ -103,7 +96,6 @@ namespace ProjectM.Client
             {
                 case StructureType.Turret: return TurretGhostMesh;
                 case StructureType.Wall: return WallGhostMesh;
-                case StructureType.Fabricator: return FabricatorGhostMesh;
                 default: return null;
             }
         }