Initial commit: ComfyUI BIM-VFI node for video frame interpolation

Wraps BiM-VFI (CVPR 2025) as a ComfyUI custom node for long video
frame interpolation with memory-safe sequential processing.

- LoadBIMVFIModel: checkpoint loader with auto-download from Google Drive
- BIMVFIInterpolate: 2x/4x/8x recursive interpolation with per-pair
  GPU processing, configurable VRAM management (all_on_gpu for high-VRAM
  setups), progress bar, and backwarp cache clearing
- Vendored inference-only architecture from KAIST-VICLab/BiM-VFI
- Auto-detection of CUDA version for cupy installation

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

utils/padder.py

@@ -0,0 +1,28 @@
+import torch.nn.functional as F
+
+
+class InputPadder:
+    """ Pads images such that dimensions are divisible by divisor """
+
+    def __init__(self, dims, divisor=16):
+        self.ht, self.wd = dims[-2:]
+        pad_ht = (((self.ht // divisor) + 1) * divisor - self.ht) % divisor
+        pad_wd = (((self.wd // divisor) + 1) * divisor - self.wd) % divisor
+        self._pad = [0, pad_wd, 0, pad_ht]
+
+    def pad(self, *inputs):
+        if len(inputs) == 1:
+            return F.pad(inputs[0], self._pad, mode='constant')
+        else:
+            return [F.pad(x, self._pad, mode='constant') for x in inputs]
+
+    def unpad(self, *inputs):
+        if len(inputs) == 1:
+            return self._unpad(inputs[0])
+        else:
+            return [self._unpad(x) for x in inputs]
+
+    def _unpad(self, x):
+        ht, wd = x.shape[-2:]
+        c = [self._pad[2], ht - self._pad[3], self._pad[0], wd - self._pad[1]]
+        return x[..., c[0]:c[1], c[2]:c[3]]