fix: Section Speed Editor에서 본 곡선 없는 클립 length 0으로 표시되는 문제 수정

- Mixamo export 클립 등 m_FloatCurves만 있는 경우 bone transform 곡선이 없어 length가 0으로 계산되던 문제 수정
- bone 곡선이 없으면 m_StopTime을 기준으로 폴백하도록 effectiveLength 로직 추가

Assets/_Game/Scripts/Editor/AnimationSectionSpeedEditor.cs

@@ -54,18 +54,28 @@ public class AnimationSectionSpeedEditor : EditorWindow
 
         // ── 클립 정보 (실제 키프레임 기반) ──
         float actualLength = GetActualLastKeyframeTime(clip);
+        bool hasBoneCurves = actualLength > 0f;
+
+        // 본 트랜스폼 곡선이 없으면 m_StopTime을 기준으로 사용
+        // (Mixamo export 클립 등 m_FloatCurves만 있는 경우)
+        float effectiveLength = hasBoneCurves ? actualLength : clip.length;
+
         EditorGUILayout.LabelField("Clip Info", EditorStyles.boldLabel);
         EditorGUI.indentLevel++;
-        EditorGUILayout.LabelField("Length (keyframes)", $"{actualLength:F3}s");
+        EditorGUILayout.LabelField("Length", $"{effectiveLength:F3}s");
-        EditorGUILayout.LabelField("m_StopTime", $"{clip.length:F3}s");
 
-        if (Mathf.Abs(clip.length - actualLength) > 0.01f)
+        if (hasBoneCurves && Mathf.Abs(clip.length - actualLength) > 0.01f)
         {
+            EditorGUILayout.LabelField("m_StopTime", $"{clip.length:F3}s");
             EditorGUILayout.HelpBox($"m_StopTime({clip.length:F3}s)이 실제 키프레임 길이({actualLength:F3}s)와 다릅니다.\n" +
                                    "스피드 변경 시 실제 키프레임 길이를 기준으로 계산합니다.", MessageType.Warning);
         }
+        else if (!hasBoneCurves)
+        {
+            EditorGUILayout.LabelField("  (본 곡선 없음, m_StopTime 기준)", EditorStyles.miniLabel);
+        }
 
-        EditorGUILayout.LabelField("Total Frames ({fps}fps)", $"{Mathf.Max(1, Mathf.FloorToInt(actualLength * fps))}");
+        EditorGUILayout.LabelField("Total Frames ({fps}fps)", $"{Mathf.Max(1, Mathf.FloorToInt(effectiveLength * fps))}");
         EditorGUI.indentLevel--;
 
         EditorGUILayout.Space();
@@ -74,7 +84,7 @@ public class AnimationSectionSpeedEditor : EditorWindow
         fps = EditorGUILayout.IntField("FPS", fps);
         fps = Mathf.Max(1, fps);
 
-        int totalFrames = Mathf.Max(1, Mathf.FloorToInt(actualLength * fps));
+        int totalFrames = Mathf.Max(1, Mathf.FloorToInt(effectiveLength * fps));
 
         // ── 프레임 범위 ──
         EditorGUILayout.LabelField("Target Frame Range", EditorStyles.boldLabel);
@@ -108,7 +118,7 @@ public class AnimationSectionSpeedEditor : EditorWindow
         EditorGUILayout.Space();
 
         // ── 타임라인 시각화 ──
-        DrawTimeline(startTime, endTime, actualLength);
+        DrawTimeline(startTime, endTime, effectiveLength);
 
         EditorGUILayout.Space();
 
@@ -133,7 +143,7 @@ public class AnimationSectionSpeedEditor : EditorWindow
         // ── 미리보기 ──
         float newDuration = duration / speedMultiplier;
         float timeDelta = newDuration - duration;
-        float newLength = actualLength + timeDelta;
+        float newLength = effectiveLength + timeDelta;
 
         EditorGUILayout.LabelField("Preview", EditorStyles.boldLabel);
         EditorGUI.indentLevel++;
@@ -301,6 +311,7 @@ public class AnimationSectionSpeedEditor : EditorWindow
         float newDuration = duration / speedMultiplier;
         float timeDelta = newDuration - duration;
         float actualLength = GetActualLastKeyframeTime(clip);
+        float effectiveLength = actualLength > 0f ? actualLength : clip.length;
 
         Undo.RegisterCompleteObjectUndo(clip, $"Section Speed {speedMultiplier}x (frames {startFrame}~{endFrame})");
 
@@ -392,7 +403,7 @@ public class AnimationSectionSpeedEditor : EditorWindow
         }
 
         // ── 5. m_StopTime 갱신 (SerializedObject로) ──
-        float newStopTime = actualLength + timeDelta;
+        float newStopTime = effectiveLength + timeDelta;
         var serializedClip = new SerializedObject(clip);
         SerializedProperty stopTimeProp = serializedClip.FindProperty("m_StopTime");
         if (stopTimeProp != null)
@@ -433,7 +444,7 @@ public class AnimationSectionSpeedEditor : EditorWindow
 
         Debug.Log($"[SectionSpeedEditor] {clip.name}: frames {startFrame}~{endFrame} → {speedMultiplier}x " +
                   $"({duration:F3}s → {newDuration:F3}s) " +
-                  $"| clip: {actualLength:F3}s → {newStopTime:F3}s " +
+                  $"| clip: {effectiveLength:F3}s → {newStopTime:F3}s " +
                   $"| curves: {modifiedCurves}, keyframes: {modifiedKeyframes}, skipped: {skippedCurves}" +
                   $" | events: {(eventsModified ? "modified" : "none")}");
     }