Reduce ZeroGPU request duration 180s -> 120s

Lowers the @spaces.GPU duration for all three models from 180s to 120s.

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=180)
-    spaces_gpu_mr = spaces.GPU(duration=180)
-    spaces_gpu_mr_brain = spaces.GPU(duration=180)
+    spaces_gpu_ct = spaces.GPU(duration=120)
+    spaces_gpu_mr = spaces.GPU(duration=120)
+    spaces_gpu_mr_brain = spaces.GPU(duration=120)
 except (ImportError, AttributeError):
     def _identity(d=None):  # noqa: ARG001
         def deco(fn):