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.Core.Net/GameEventWiring.cs

@@ -394,6 +394,13 @@ public static class GameEventWiring
         registrar.Register(GameEventType.ApproachVendor, e =>
         {
             var p = VendorApproach.TryParse(e.Payload.Span);
+            if (VendorDiagnostics.DumpVendorEnabled)
+            {
+                Console.WriteLine(
+                    $"[vendor-diag] ApproachVendor(0x0062) inbound parsed={p is not null} "
+                    + $"vendorGuid={(p is null ? "n/a" : $"0x{p.Value.VendorGuid:X8}")} "
+                    + $"itemCount={(p is null ? "n/a" : p.Value.Items.Count.ToString())}");
+            }
             if (p is null) return;
 
             var profile = new VendorShopProfile(
@@ -411,6 +418,14 @@ public static class GameEventWiring
             for (int i = 0; i < shopItems.Length; i++)
             {
                 VendorApproach.ItemProfile item = p.Value.Items[i];
+                if (VendorDiagnostics.DumpVendorEnabled && i < 5)
+                {
+                    Console.WriteLine(
+                        $"[vendor-diag] ApproachVendor wire-item[{i}] guid=0x{item.ItemGuid:X8} "
+                        + $"name={item.Desc.Name ?? "null"} "
+                        + $"descStackSize={(item.Desc.StackSize is { } ds ? ds.ToString() : "null")} "
+                        + $"stackSizeMax={(item.Desc.StackSizeMax is { } sm ? sm.ToString() : "null")}");
+                }
                 shopItems[i] = new VendorShopItem(
                     item.ItemGuid,
                     item.StackSize,
@@ -502,6 +517,12 @@ public static class GameEventWiring
         registrar.Register(GameEventType.UseDone, e =>
         {
             uint? err = GameEvents.ParseUseDone(e.Payload.Span);
+            if (VendorDiagnostics.DumpVendorEnabled)
+            {
+                Console.WriteLine(
+                    $"[vendor-diag] UseDone(0x01C7) inbound parsed={err is not null} "
+                    + $"err={(err is null ? "n/a" : $"0x{err.Value:X4}")}");
+            }
             if (err is null) return;
             Console.WriteLine($"[use-done] err=0x{err.Value:X4}");
             onUseDone?.Invoke(err.Value);