fix(D.2b): wield is ContainerId-based — drop the WielderId write (code review)

Code-quality review (needs-changes) on Task 3: WieldItemOptimistic wrote
item.WielderId directly, but RollbackMove (via MoveItem) never cleared it
→ a wield-rollback left a pack item with a stale WielderId=player.

Root-cause fix (vs the reviewer's snapshot-WielderId suggestion): acdream's
existing WieldObject 0x0023 confirm models a wielded item as ContainerId=
wielder + equip=mask and does NOT touch WielderId. So the optimistic path
must match — drop the WielderId write entirely. Optimistic state now equals
the confirmed state, rollback fully restores through MoveItem alone, and the
stale-state class is structurally eliminated. The paperdoll's
(WielderId==p || ContainerId==p) filter still matches optimistic wields via
ContainerId (login-equipped items match via WielderId from their CreateObject).

Also: + the wield+move outstanding-count combo test (spec §8), MoveItem doc
note that it doesn't manage WielderId, and the test pins WielderId==0 post-
optimistic-wield to document the model. Core 74/74 green.

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

docs/superpowers/plans/2026-06-22-d2b-paperdoll-slice1-equip-slots.md

@@ -566,7 +566,7 @@ public class PaperdollControllerTests
         var payload = new ItemDragPayload(0xD01u, ItemDragSource.Inventory, 0, lists[HeadSlot].Cell);
         ctrl.HandleDropRelease(lists[HeadSlot], lists[HeadSlot].Cell, payload);
         Assert.Equal(EquipMask.HeadWear, objects.Get(0xD01u)!.CurrentlyEquippedLocation); // equipped instantly
-        Assert.Equal(Player, objects.Get(0xD01u)!.WielderId);
+        Assert.Equal(Player, objects.Get(0xD01u)!.ContainerId);     // contained-by-wielder (the optimistic wield is ContainerId-based; it does NOT write WielderId)
         Assert.Single(wields);
         Assert.Equal((0xD01u, (uint)EquipMask.HeadWear), wields[0]);                       // GetAndWieldItem wire
     }