Runtime fallback: install local detectron2 if import fails (no build isolation)

mvp.py

@@ -63,8 +63,7 @@ MK_PATH = os.path.join(REPO_ROOT, "MaskClustering")
 #     import detectron2  # noqa: F401
 
 # If detectron2 isn't installed as a package, allow importing from vendored source.
-if os.path.isdir(DETECTRON2_ROOT) and DETECTRON2_ROOT not in sys.path:
-    sys.path.append(DETECTRON2_ROOT)
+
 
 # Writable workdir (HF Spaces: prefer /tmp)
 WORK_DIR = os.environ.get("ZOO3D_WORKDIR", os.path.join(tempfile.gettempdir(), "zoo3d"))