Remove cupy auto-install from __init__.py

No more pip calls at import time. Users get a clear error with
install instructions from the Load node if cupy is missing.

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

__init__.py

@@ -1,40 +1,3 @@
-import subprocess
-import sys
-import logging
-
-logger = logging.getLogger("Tween")
-
-
-def _ensure_cupy():
-    """Try to auto-install cupy if missing, matching the PyTorch CUDA version."""
-    try:
-        import cupy  # noqa: F401
-        return
-    except ImportError:
-        pass
-
-    try:
-        import torch
-        if not torch.cuda.is_available() or not hasattr(torch.version, "cuda") or torch.version.cuda is None:
-            logger.warning(
-                "[Tween] CUDA not available — cupy cannot be installed. "
-                "SGM-VFI and GIMM-VFI require CUDA."
-            )
-            return
-        major = int(torch.version.cuda.split(".")[0])
-        cupy_pkg = f"cupy-cuda{major}x"
-        logger.info(f"[Tween] Installing {cupy_pkg} (CUDA {torch.version.cuda})...")
-        subprocess.check_call([sys.executable, "-m", "pip", "install", cupy_pkg])
-    except Exception as e:
-        logger.warning(
-            f"[Tween] Could not auto-install cupy: {e}\n"
-            f"[Tween] SGM-VFI and GIMM-VFI will not work without cupy. Install manually:\n"
-            f"[Tween]   pip install cupy-cuda12x  # replace 12 with your CUDA major version"
-        )
-
-
-_ensure_cupy()
-
 from .nodes import (
     LoadBIMVFIModel, BIMVFIInterpolate, BIMVFISegmentInterpolate, TweenConcatVideos,
     LoadEMAVFIModel, EMAVFIInterpolate, EMAVFISegmentInterpolate,