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/Simulation/Building/StructureComponents.cs

@@ -76,4 +76,12 @@ namespace ProjectM.Simulation
 
     /// <summary>Tag on the baked singleton carrying the <see cref="StructureCatalogEntry"/> buffer (the build cost/prefab table).</summary>
     public struct StructureCatalog : IComponentData { }
+
+    /// <summary>
+    /// Marks a structure PLACED by a player at runtime (BuildPlaceSystem) or restored from a save — i.e. the
+    /// persistable set, as opposed to anything baked into the subscene. SaveWriteSystem scans only these and
+    /// BaseRestoreSystem re-adds the tag, so save/restore is the single source of truth for player builds.
+    /// Server-only (not replicated). (Re-homed here from the retired automation components — LANTERN purge.)
+    /// </summary>
+    public struct RuntimePlacedTag : IComponentData { }
 }