Fix GPU config: lazy initialization to avoid import-time error

modal.gpu is not available at module import time. Move GPU object
creation to a function called at runtime only when gpu: label is present.

Author: manascb1344

app.py

@@ -93,14 +93,24 @@ def format(self, record: logging.LogRecord) -> str:
     if MAX_CONCURRENT_PER_REPO <= 0:
         MAX_CONCURRENT_PER_REPO = None
 
-GPU_MAP = {
-    "t4": modal.gpu.T4(),
-    "l4": modal.gpu.L4(),
-    "a100": modal.gpu.A100(),
-    "a100-80gb": modal.gpu.A100_80GB(),
-    "h100": modal.gpu.H100(),
+GPU_LABEL_TO_ATTR = {
+    "t4": "T4",
+    "l4": "L4",
+    "a100": "A100",
+    "a100-80gb": "A100_80GB",
+    "h100": "H100",
 }
 
+
+def _get_gpu_config(gpu_key: str):
+    attr_name = GPU_LABEL_TO_ATTR.get(gpu_key)
+    if attr_name is None:
+        return None
+    gpu_cls = getattr(modal.gpu, attr_name, None)
+    if gpu_cls is None:
+        return None
+    return gpu_cls()
+
 # =============================================================================
 # TRUST MODEL
 # =============================================================================
@@ -488,7 +498,7 @@ async def github_webhook(request: Request):
     for label in job_labels:
         if label.startswith("gpu:"):
             gpu_key = label.split(":", 1)[1].lower()
-            gpu_config = GPU_MAP.get(gpu_key)
+            gpu_config = _get_gpu_config(gpu_key)
             if not gpu_config:
                 logger.warning(
                     "Unknown GPU type requested",