fix(core+app): Phase 6.8 — keep NPCs animated when post-spawn motion update is unmappable

User reported that some NPCs (Pathwarden, Town Crier) didn't breathe.
Diagnostic logging revealed:

1. Both NPCs are correctly registered as animated at CreateObject
   time with the standard 30fps human breath cycle (anim=0x03000001).
2. Immediately after spawn the server sends an UpdateMotion with
   stance=0x0003 cmd=0x0000 for these NPCs.
3. MotionResolver.GetIdleCycle returned NULL for that combination,
   because StyleDefaults didn't have an entry for stance=3.
4. OnLiveMotionUpdated treated the NULL as "switch to a static pose"
   and removed the entity from _animatedEntities.

Two fixes:

A. MotionResolver.ResolveIdleCycleInternal — when stance is set but
   StyleDefaults has no entry for it, fall back to the table's
   DefaultStyle/DefaultSubstate instead of returning null. The
   server-supplied stance was just an unmappable override; the table
   default is the correct "I have no better information" answer.
   Pulled the table-default lookup into a small TryGetTableDefault
   helper so both fallback paths use the same code.

B. OnLiveMotionUpdated — never REMOVE an animated entity. If the
   re-resolved cycle is bad (null, framerate=0, or single-frame),
   leave the existing cycle running so the entity continues to
   breathe with whatever it already had. The defensive "remove on
   re-resolve failure" was the bug — it silently un-registered NPCs
   the moment the server sent any partial motion update.

Together these mean: any NPC that successfully registers as animated
at spawn stays animated, even if the server's subsequent motion
updates are incomplete or use stance values our resolver doesn't
have a mapping for.

Strips the [BREATHE] and [MOTION] diagnostic spew added during the
investigation now that the cause is identified.

220 tests still green.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/AcDream.App/Rendering/GameWindow.cs

@@ -689,6 +689,7 @@ public sealed class GameWindow : IDisposable
             _liveAnimRejectPartFrames++;
 
 
+
         if (idleCycle is not null && idleCycle.Framerate != 0f
             && idleCycle.HighFrame > idleCycle.LowFrame
             && idleCycle.Animation.PartFrames.Count > 1)
@@ -783,18 +784,22 @@ public sealed class GameWindow : IDisposable
             stanceOverride: stance,
             commandOverride: command);
 
-        if (newCycle is null || newCycle.Framerate == 0f
-            || newCycle.HighFrame <= newCycle.LowFrame
-            || newCycle.Animation.PartFrames.Count <= 1)
-        {
-            // New pose is a static one — stop animating and leave the
-            // entity on its last rendered frame. Removing from the map
-            // means the tick no longer updates it.
-            _animatedEntities.Remove(entity.Id);
-            return;
-        }
+        // If the new cycle is bad (null, framerate=0, or single-frame), do
+        // NOT remove the entity from the animated set. Keep its existing
+        // cycle running so it continues to breathe / idle. Removing on
+        // re-resolve failure was a bug that silently unregistered NPCs the
+        // moment the server sent a motion update with a stance/command
+        // pair the resolver couldn't translate cleanly. Defensive: switch
+        // only when we have a clearly better cycle.
+        bool newCycleIsGood = newCycle is not null
+            && newCycle.Framerate != 0f
+            && newCycle.HighFrame > newCycle.LowFrame
+            && newCycle.Animation.PartFrames.Count > 1;
 
-        ae.Animation = newCycle.Animation;
+        if (!newCycleIsGood)
+            return;
+
+        ae.Animation = newCycle!.Animation;
         ae.LowFrame = Math.Max(0, newCycle.LowFrame);
         ae.HighFrame = Math.Min(newCycle.HighFrame, newCycle.Animation.PartFrames.Count - 1);
         ae.Framerate = newCycle.Framerate;

src/AcDream.Core/Meshing/MotionResolver.cs

@@ -162,6 +162,21 @@ public static class MotionResolver
         uint styleVal;
         uint substateVal;
 
+        // Helper: pick the table's default (style, substate) — used as the
+        // ultimate fallback when caller-supplied overrides don't resolve.
+        bool TryGetTableDefault(out uint styleOut, out uint substateOut)
+        {
+            if (mtable.StyleDefaults.TryGetValue(mtable.DefaultStyle, out var defaultSubstate))
+            {
+                styleOut = (uint)mtable.DefaultStyle;
+                substateOut = (uint)defaultSubstate;
+                return true;
+            }
+            styleOut = 0;
+            substateOut = 0;
+            return false;
+        }
+
         if (stanceOverride is { } stance && stance != 0)
         {
             styleVal = stance;
@@ -175,15 +190,22 @@ public static class MotionResolver
             }
             else
             {
-                return null;
+                // The server gave us a stance the motion table doesn't recognize
+                // (e.g. NPCs that re-broadcast a "ready" stance with a substate
+                // value where the table only has a style entry). Don't return
+                // null — fall back to the table default so the entity at least
+                // animates with its idle cycle. Returning null here was the
+                // bug that silently un-registered Pathwarden / Town Crier from
+                // _animatedEntities the moment ACE sent a post-spawn motion
+                // update with stance=0x0003 cmd=0x0000.
+                if (!TryGetTableDefault(out styleVal, out substateVal))
+                    return null;
             }
         }
         else
         {
-            if (!mtable.StyleDefaults.TryGetValue(mtable.DefaultStyle, out var defaultSubstate))
+            if (!TryGetTableDefault(out styleVal, out substateVal))
                 return null;
-            styleVal = (uint)mtable.DefaultStyle;
-            substateVal = (uint)defaultSubstate;
         }
 
         // ACViewer's cycle key encoding (Physics/Animation/MotionTable.cs:191):