fix: show interactive window when plot_wave_save_gif/mp4 are both 0

Use Agg backend and show=False only when saving to file.
When neither gif nor mp4 is requested, show the animation window interactively.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

dynamics.py

@@ -381,15 +381,19 @@ def run_case(config_path, runtime_base, input_dir="input", output_dir="output",
         # 6. 波形能量动画（可选）
         if config.get("step_plot_wave", 0):
             try:
-                import matplotlib
+                _save_gif = int(config.get("plot_wave_save_gif", 0))
-                matplotlib.use("Agg")   # 非交互式后端，避免弹窗/报错
+                _save_mp4 = int(config.get("plot_wave_save_mp4", 0))
+                _to_file  = bool(_save_gif or _save_mp4)
+                if _to_file:
+                    import matplotlib
+                    matplotlib.use("Agg")   # 保存文件时用非交互式后端
                 import plot_wave as pw
                 print("[run] 正在绘制波形与能量图…")
                 gif = pw.plot_wave(
                     str(output_dir_abs),
-                    save_gif=int(config.get("plot_wave_save_gif", 0)),
+                    save_gif=_save_gif,
-                    save_mp4=int(config.get("plot_wave_save_mp4", 0)),
+                    save_mp4=_save_mp4,
-                    show=False,
+                    show=not _to_file,   # 不保存文件时弹出交互窗口
                 )
                 if gif:
                     print(f"[run] 波形 GIF 已保存: {gif}")