feat: imaging tensor loaders + change hash

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

gates/imaging.py

@@ -0,0 +1,30 @@
+"""Tensor/imaging helpers (torch + PIL). No comfy imports."""
+import hashlib
+import numpy as np
+import torch
+from PIL import Image, ImageOps
+
+
+def load_image_tensor(path):
+    img = Image.open(path)
+    img = ImageOps.exif_transpose(img).convert("RGB")
+    arr = np.array(img, dtype=np.float32) / 255.0
+    return torch.from_numpy(arr).unsqueeze(0)          # [1,H,W,3]
+
+
+def load_mask_tensor(path, h, w):
+    if not path:
+        return torch.zeros((1, h, w), dtype=torch.float32)
+    m = Image.open(path).convert("L")
+    arr = np.array(m, dtype=np.float32) / 255.0
+    return torch.from_numpy(arr).unsqueeze(0)          # [1,H,W]
+
+
+def empty_outputs():
+    return (torch.zeros((1, 1, 1, 3), dtype=torch.float32),
+            torch.zeros((1, 1, 1), dtype=torch.float32))
+
+
+def change_hash(pool_id, index, mtimes):
+    key = f"{pool_id}|{index}|" + "|".join(f"{t:.3f}" for t in mtimes)
+    return hashlib.sha256(key.encode()).hexdigest()