docs: improve CI and testing documentation (#21202)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sgl-kernel/tests/test_moe_align.py

@@ -1,4 +1,5 @@
 import itertools
+import sys
 
 import pytest
 import torch
@@ -271,4 +272,4 @@ def test_moe_sum(m: int, topk: int, k: int, dtype: torch.dtype):
 
 
 if __name__ == "__main__":
-    pytest.main([__file__])
+    sys.exit(pytest.main([__file__]))