Fix MaleExplorer setup with shadow material and editor diagnostics.

Improve FBX/prefab import setup, CharacterSpawner, and add M3 inspect/rebuild helpers.

Co-authored-by: Cursor <cursoragent@cursor.com>

AIClient/Assets/Editor/M3/InspectMaleExplorerMesh.cs

@@ -0,0 +1,47 @@
+using System.Text;
+using UnityEditor;
+using UnityEngine;
+
+public static class InspectMaleExplorerMesh
+{
+    public static string Execute()
+    {
+        const string fbx = "Assets/Bundles/Characters/MaleExplorer/MaleExplorer.fbx";
+        const string prefabPath = "Assets/Bundles/Characters/MaleExplorer/MaleExplorer.prefab";
+        var sb = new StringBuilder();
+
+        foreach (var obj in AssetDatabase.LoadAllAssetsAtPath(fbx))
+        {
+            if (obj is Mesh mesh)
+            {
+                sb.AppendLine(
+                    $"assetMesh={mesh.name} verts={mesh.vertexCount} bounds={mesh.bounds} " +
+                    $"tris={mesh.triangles.Length / 3}");
+            }
+        }
+
+        var prefab = AssetDatabase.LoadAssetAtPath<GameObject>(prefabPath);
+        var go = (GameObject)PrefabUtility.InstantiatePrefab(prefab);
+        go.transform.position = Vector3.zero;
+        go.transform.localScale = Vector3.one;
+        foreach (var mf in go.GetComponentsInChildren<MeshFilter>(true))
+        {
+            var m = mf.sharedMesh;
+            if (m == null) continue;
+            sb.AppendLine($"filter={mf.name} localScale={mf.transform.lossyScale} meshBounds={m.bounds} worldBounds={mf.GetComponent<Renderer>().bounds}");
+            // sample a few verts
+            var vs = m.vertices;
+            var min = vs[0];
+            var max = vs[0];
+            for (int i = 1; i < vs.Length; i++)
+            {
+                min = Vector3.Min(min, vs[i]);
+                max = Vector3.Max(max, vs[i]);
+            }
+            sb.AppendLine($"vertMin={min} vertMax={max} size={max - min}");
+        }
+
+        Object.DestroyImmediate(go);
+        return sb.ToString();
+    }
+}