fix(vendor): evidence-based pass — max-first stack ceiling; the local player resolves never-animated MoveTo targets

Both chains pinned by the live [vendor-diag] run (vendor-diag.log)
after three code-reading rounds each failed:

The split bar: ACE serializes descStackSize=1 for EVERY browse row
(live wire, log 343-348) — the R1-era "ACE never populates desc"
claim is retracted with the line quoted. Retail's vendor sites read
pwd._maxStackSize directly (four sites, incl. UpdateItemsList
@0x004c1ea0 stamping min(remaining, _maxStackSize));
ResolveAuthoredStackSize flips to max-first for its vendor-only
consumers. Taper ceiling 1000, scarab 100, seed 1 for exempt.
Pricing still reads the desc (per-1 values on ACE).

Walk-to-use: the local player's getObjectA seam was bound to
TryGetPhysicsHost, which resolves only INSTALLED physics hosts — a
never-animated vendor has none, so TargetManager.SetTarget got null,
the MoveToObject armed with zero nodes, and UseTime never dispatched.
The log's natural=False completions were the user's own movement keys
(retail-correct input-edge cancels); attempt 4 worked because the
greeting animation had installed a host. RuntimePhysicsState gains
the retail CObjectMaint::GetObjectA seam (bound canonical resolver
with installed-host fallback); the graphical host binds the SAME
lazy-minimal-host resolver every remote already uses — whose own doc
comment names this exact never-animated hazard. The reservation
release was already correct (2b premise refuted with evidence); the
production-wiring invariants are now pinned by four new tests
including the pre-fix pathology as a permanent sabotage control.

AP-169 rewritten a second time, honestly. The [vendor-diag] probe
family (ACDREAM_DUMP_VENDOR) lands env-gated for future live triage.

Clean-room complete solution: 11,536 passed / 4 skipped / 0 failed.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/AcDream.App/Interaction/PlayerInteractionMovementSink.cs

@@ -1,4 +1,5 @@
 using AcDream.App.Input;
+using AcDream.Core.Items;
 using AcDream.Core.Physics;
 using AcDream.Core.Physics.Motion;
 
@@ -60,6 +61,14 @@ internal sealed class PlayerInteractionMovementSink(
             Height = approach.TargetHeight,
         };
 
+        if (VendorDiagnostics.DumpVendorEnabled)
+        {
+            Console.WriteLine(
+                $"[vendor-diag] BeginApproach guid=0x{approach.Target.ServerGuid:X8} "
+                + $"movementType={movement.Type} distanceToObject={parameters.DistanceToObject} "
+                + $"canCharge={parameters.CanCharge} target=0x{movement.ObjectId:X8}");
+        }
+
         // PerformMovement cancels at its head. Do it explicitly before the
         // intent is armed so cancellation of the preceding move cannot clear
         // the new request; the internal second call is then a retail no-op.