fix(core): resolve AnimData HighFrame=-1 sentinel before filtering cycles

Diagnostic spawn dump revealed the player character arrives with
`low=0 high=-1 framerate=30.00 partFrames=33`. The -1 is ACViewer's
"play the whole animation" sentinel (see
references/ACViewer/.../Physics/Animation/AnimSequenceNode.cs:96-113
set_animation_id). My Phase 6.1 code used the raw int values, so
the downstream registration filter evaluated `HighFrame(-1) > LowFrame(0)`
as false and threw away every animated entity whose AnimData used the
sentinel — which, from the live dump, appears to be basically all of
them.

MotionResolver.GetIdleCycle now does the same four-step clamp ACViewer
does: -1 HighFrame → NumFrames-1, clamp LowFrame and HighFrame to
NumFrames-1, and collapse to LowFrame if LowFrame > HighFrame. The
IdleCycle carried up to GameWindow is always in terms of real frame
indices the playback loop can step through. Static poses (framerate==0
or single frame after resolution) still skip registration correctly.

168 tests green.

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

src/AcDream.App/Rendering/GameWindow.cs

@@ -946,6 +946,23 @@ public sealed class GameWindow : IDisposable
         else if (idleCycle.Animation.PartFrames.Count <= 1)
             _liveAnimRejectPartFrames++;
 
+        // Per-entity dump for the first N spawns so we can see actual
+        // AnimData values for live creatures and compare against retail.
+        if (_liveSpawnReceived <= 30)
+        {
+            if (idleCycle is not null)
+                Console.WriteLine($"live: SPAWN[{_liveSpawnReceived}] name='{spawn.Name ?? "?"}' " +
+                                  $"setup=0x{spawn.SetupTableId:X8} mt=0x{(spawn.MotionTableId ?? 0):X8} " +
+                                  $"cycle: anim=0x{(uint)idleCycle.Animation.Id:X8} " +
+                                  $"low={idleCycle.LowFrame} high={idleCycle.HighFrame} " +
+                                  $"framerate={idleCycle.Framerate:F2} partFrames={idleCycle.Animation.PartFrames.Count} " +
+                                  $"numParts={idleCycle.Animation.NumParts}");
+            else
+                Console.WriteLine($"live: SPAWN[{_liveSpawnReceived}] name='{spawn.Name ?? "?"}' " +
+                                  $"setup=0x{spawn.SetupTableId:X8} mt=0x{(spawn.MotionTableId ?? 0):X8} " +
+                                  $"cycle=null (no motion table / resolver failed)");
+        }
+
         if (idleCycle is not null && idleCycle.Framerate != 0f
             && idleCycle.HighFrame > idleCycle.LowFrame
             && idleCycle.Animation.PartFrames.Count > 1)

src/AcDream.Core/Meshing/MotionResolver.cs

@@ -78,7 +78,39 @@ public static class MotionResolver
         var resolved = ResolveIdleCycleInternal(setup, dats, motionTableIdOverride, stanceOverride, commandOverride);
         if (resolved is null) return null;
         var (anim, ad) = resolved.Value;
-        return new IdleCycle(anim, ad.LowFrame, ad.HighFrame, ad.Framerate);
+
+        // Sentinel resolution — matches ACViewer's AnimSequenceNode.set_animation_id
+        // (references/ACViewer/.../Physics/Animation/AnimSequenceNode.cs:96-113).
+        //
+        // AnimData in the dats encodes a few sentinel values that the raw int
+        // fields can't represent directly:
+        //   * HighFrame == -1    → "play the whole animation" (use NumFrames - 1)
+        //   * HighFrame > NumFrames - 1 → clamp (defensive for malformed data)
+        //   * LowFrame >= NumFrames → clamp to NumFrames - 1
+        //   * LowFrame > HighFrame after clamping → collapse to a single frame
+        //
+        // Our Phase 6.1 code naively used the raw LowFrame/HighFrame and then
+        // rejected the cycle if `HighFrame <= LowFrame`, which silently threw
+        // away every animated creature whose AnimData used the -1 sentinel —
+        // i.e. almost all of them. Resolving here makes the IdleCycle carry
+        // the real frame range, so downstream playback/filtering sees a span
+        // it can advance through.
+        int numFrames = anim.PartFrames.Count;
+        int lowFrame = ad.LowFrame;
+        int highFrame = ad.HighFrame;
+
+        if (highFrame < 0)
+            highFrame = numFrames - 1;
+        if (lowFrame >= numFrames)
+            lowFrame = numFrames - 1;
+        if (highFrame >= numFrames)
+            highFrame = numFrames - 1;
+        if (lowFrame < 0)
+            lowFrame = 0;
+        if (lowFrame > highFrame)
+            highFrame = lowFrame;
+
+        return new IdleCycle(anim, lowFrame, highFrame, ad.Framerate);
     }
 
     public static AnimationFrame? GetIdleFrame(