- Move imports to module level in all *_core.py test files (16 files)
- Remove try/except/skip patterns from integration tests
- Remove @pytest.mark.skip decorators from gradient flow tests
- Convert environment validation skips to warnings for optional checks
- Change milestone tests from skip to fail when scripts missing
Tests now either pass or fail - no silent skipping that hides issues.
This ensures the test suite provides accurate feedback about what works.
Verifies that matmul correctly raises ValueError when given 0D tensors
(scalars), ensuring behavior aligns with PyTorch/NumPy semantics.
Follow-up to PR #1120.