Remove default branch assignment for layered image type in _resolve_musubi_target function in app.py. This change simplifies branch handling by eliminating the automatic assignment of a specific branch when no branch is set, enhancing clarity in target resolution logic.

app.py

@@ -71,8 +71,6 @@ def _resolve_musubi_target(image_type: str) -> Tuple[str, str]:
         target = "/musubi-tuner-layered" if image_type == "layered" else "/musubi-tuner"
 
     branch = os.environ.get("MUSUBI_TUNER_BRANCH", "").strip()
-    if not branch and image_type == "layered":
-        branch = "feat-qwen-image-layered"
     return target, branch