adding F-contig layout support + other cleanups

[SwayamInSync]

closes #89

This PR improves the BLAS integration very parallel to the NumPy's own logic.

• Mirrors NumPy's own @TYPE@_matmul dispatch. NumPy hands the inner loop raw strides and expects the loop itself to dispatch, so we do the same instead of assuming row-major.
• Ports NumPy's is_blasable2d check: an operand is BLAS-able iff its fast axis is contiguous and the slow axis is a valid leading dimension; each operand is tested in both orientations (C- and F-blasable).
• BLAS-able operands are passed to QBLAS zero-copy with the matching transpose flag ('N'/'T') and lda derived from strides, so F-contiguous/transposed inputs need no copy (QBLAS already supports transa/transb correctly).
• Non-BLAS-able operands (fully strided, negative strides) and non-row-major output are gathered into contiguous temps and scattered back, exactly NumPy's copy fallback.
• Oversized (dim > INT_MAX) or empty cores fall back to the naive strided loop, matching NumPy's too_big_for_blas guard.

I think this is a good base to integrate dot operations efficiently in follow-up PRs

[SwayamInSync]

Ahh the fix to run older-cpu workflows is done in #104 , once that will merge we can update here.

[Copilot]

Pull request overview

This PR fixes incorrect matmul results for non-row-major (notably F-contiguous and transposed-view) QuadPrecision inputs by making the QBLAS dispatch stride-aware (mirroring NumPy’s layout/BLAS-ability checks) and expanding test coverage to exercise the full layout matrix and copy-fallback paths.

Changes:

• Update the matmul strided loop to detect BLAS-able 2D operands in either orientation and pass the appropriate transa/transb + lda/ldb/ldc, copying only when required.
• Remove the prior xfails for Fortran-order/transposed batched cases and add new tests covering layout combinations, output layout, empty-core behavior, and copy-fallback scenarios.
• Adjust QBLAS interface edge handling for empty GEMV/GEMM calls.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
tests/test_dot.py	Removes xfails for issue #89 and adds comprehensive layout/copy-path tests for matmul.
src/csrc/umath/matmul.cpp	Implements stride-derived BLAS dispatch (incl. transpose flags) plus gather/scatter copy fallback and size/empty guards.
src/csrc/quadblas_interface.cpp	Tweaks empty-dimension behavior for qblas_gemv and qblas_gemm.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.