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/Simulation/Combat/AbilityFireSystem.cs

@@ -143,17 +143,9 @@ namespace ProjectM.Simulation
                             });
                             // C3: the cone reads as weak vs the melee cleave without knockback — stamp it like melee
                             // (guarded: dummies lack KnockbackState → ECB throw; the boss is knockback-immune, A4).
-                            if (m_KnockbackLookup.HasComponent(coneTargets[ci]) && !m_BossLookup.HasComponent(coneTargets[ci]))
-                            {
-                                float3 kd3 = coneTargetPos[ci] - xform.ValueRO.Position;
-                                float2 kdir = math.lengthsq(kd3.xz) > 1e-6f ? math.normalize(kd3.xz) : cFace;
-                                m_KnockbackLookup[coneTargets[ci]] = new KnockbackState
-                                {
-                                    Dir = kdir,
-                                    Speed = Tuning.KnockbackSpeed,
-                                    UntilTick = TickUtil.NonZero(serverTick.TickIndexForValidTick + (uint)math.max(1, Tuning.KnockbackDurationTicks)),
-                                };
-                            }
+                            KnockbackUtil.Stamp(ref m_KnockbackLookup, m_BossLookup, coneTargets[ci],
+                                xform.ValueRO.Position, coneTargetPos[ci], cFace, Tuning.KnockbackSpeed,
+                                TickUtil.NonZero(serverTick.TickIndexForValidTick + (uint)math.max(1, Tuning.KnockbackDurationTicks)));
                         }
                     }
                     uint coneCd = (uint)math.max(1, eff.ValueRO.CooldownTicks);