Auto-install cupy and gdown on first node load

Detects missing deps when ComfyUI imports the node and installs
them automatically via pip. No manual steps needed in Docker.

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

__init__.py

@@ -1,3 +1,35 @@
+import subprocess
+import sys
+import logging
+
+logger = logging.getLogger("BIM-VFI")
+
+
+def _auto_install_deps():
+    """Auto-install missing dependencies on first load."""
+    # gdown
+    try:
+        import gdown  # noqa: F401
+    except ImportError:
+        logger.info("[BIM-VFI] Installing gdown...")
+        subprocess.check_call([sys.executable, "-m", "pip", "install", "gdown"])
+
+    # cupy
+    try:
+        import cupy  # noqa: F401
+    except ImportError:
+        try:
+            import torch
+            major = int(torch.version.cuda.split(".")[0])
+            cupy_pkg = f"cupy-cuda{major}x"
+            logger.info(f"[BIM-VFI] Installing {cupy_pkg} (CUDA {torch.version.cuda})...")
+            subprocess.check_call([sys.executable, "-m", "pip", "install", cupy_pkg])
+        except Exception as e:
+            logger.warning(f"[BIM-VFI] Could not auto-install cupy: {e}")
+
+
+_auto_install_deps()
+
 from .nodes import LoadBIMVFIModel, BIMVFIInterpolate
 
 NODE_CLASS_MAPPINGS = {