Hygiene B4c: clean dedup helpers (knockback, bakers, editor rig)

- KnockbackUtil.Stamp: shared knockback-stamp used by AbilityFireSystem + MeleeComboSystem (guard + planar normalize + write; speed passed in).
- BakerStructureExt: AddPlacedStructure/AddDamageable extensions on Baker<T>; rewired Turret/Structure/Harvester/Conveyor/Fabricator bakers (baked data + serialized fields unchanged).
- EnemyPrefabBakeExt.AddEnemyPrefabPool: shared prefab-buffer bake for ZoneEnemyDirector/WaveDirector authoring (fields stay flat — no serialization change).
- Editor AnimRigUtil (HasParam + root-yaw overlay clip) shared by PlayerRigTools/EnemyRigTools; EnemyRigTools.MakeMat now GUID-preserving (CopySerialized over existing) — the composite AnimatorController copy left as-is with a caveat comment.

466/466 EditMode tests pass, 0 warnings.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Assets/_Project/Scripts/Authoring/Automation/ConveyorAuthoring.cs

@@ -21,13 +21,7 @@ namespace ProjectM.Authoring
             public override void Bake(ConveyorAuthoring authoring)
             {
                 var entity = GetEntity(authoring, TransformUsageFlags.Dynamic);
-                AddComponent(entity, new PlacedStructure
-                {
-                    Type = StructureType.Conveyor,
-                    Cell = default,
-                    NextTick = 0u,
-                    LastProcessedTick = 0u,
-                });
+                this.AddPlacedStructure(entity, StructureType.Conveyor);
                 AddComponent(entity, new Conveyor
                 {
                     Direction = authoring.Direction,

Assets/_Project/Scripts/Authoring/Automation/FabricatorAuthoring.cs

@@ -30,13 +30,7 @@ namespace ProjectM.Authoring
             public override void Bake(FabricatorAuthoring authoring)
             {
                 var entity = GetEntity(authoring, TransformUsageFlags.Dynamic);
-                AddComponent(entity, new PlacedStructure
-                {
-                    Type = StructureType.Fabricator,
-                    Cell = default,
-                    NextTick = 0u,
-                    LastProcessedTick = 0u,
-                });
+                this.AddPlacedStructure(entity, StructureType.Fabricator);
                 AddComponent(entity, new Fabricator
                 {
                     InResourceId = authoring.InResourceId,
@@ -52,9 +46,7 @@ namespace ProjectM.Authoring
                 // machine, diverging from DR-032. Now that it IS targetable, the DamageEvent buffer must exist
                 // (an AI strike appends into it; absent = ECB-playback throw) + Destructible lets
                 // HealthApplyDamageSystem destroy it at 0 (occupancy auto-frees).
-                AddComponent(entity, new Health { Current = authoring.MaxHp, Max = authoring.MaxHp });
-                AddBuffer<DamageEvent>(entity);
-                AddComponent<Destructible>(entity);
+                this.AddDamageable(entity, authoring.MaxHp);
             }
         }
     }

Assets/_Project/Scripts/Authoring/Automation/HarvesterAuthoring.cs

@@ -22,13 +22,7 @@ namespace ProjectM.Authoring
             public override void Bake(HarvesterAuthoring authoring)
             {
                 var entity = GetEntity(authoring, TransformUsageFlags.Dynamic);
-                AddComponent(entity, new PlacedStructure
-                {
-                    Type = StructureType.Harvester,
-                    Cell = default,
-                    NextTick = 0u,
-                    LastProcessedTick = 0u,
-                });
+                this.AddPlacedStructure(entity, StructureType.Harvester);
                 AddComponent(entity, new Harvester
                 {
                     ResourceId = authoring.OutputResourceId,