Use official ACE-Step demo approach: dtype as string (bfloat16)

acestep/handler.py

@@ -497,8 +497,7 @@ class AceStepHandler:
                                 acestep_v15_checkpoint_path,
                                 trust_remote_code=True,
                                 attn_implementation=candidate,
-                                torch_dtype=self.dtype,
-                                device_map={"": self.device},  # Force all components to target device immediately
+                                dtype="bfloat16"  # Use string like official demo
                             )
                             attn_implementation = candidate
                             break