Tune ZeroGPU durations: CT 90s, MR/MR-Brain 60s

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app.py

@@ -44,9 +44,9 @@ _ensure_upstream()
 # ZeroGPU decorator — present on HF Spaces, optional locally.
 try:
     import spaces  # type: ignore
-    spaces_gpu_ct = spaces.GPU(duration=120)
-    spaces_gpu_mr = spaces.GPU(duration=120)
-    spaces_gpu_mr_brain = spaces.GPU(duration=120)
+    spaces_gpu_ct = spaces.GPU(duration=90)
+    spaces_gpu_mr = spaces.GPU(duration=60)
+    spaces_gpu_mr_brain = spaces.GPU(duration=60)
 except (ImportError, AttributeError):
     def _identity(d=None):  # noqa: ARG001
         def deco(fn):