[FEAT] Adding vecdot implementation

[SwayamInSync]

Implementing NumPy's vecdot for quaddtype

AI declaration:
Claude is used to extend test_dot.py for adding test related vecdot and possible edge cases

[SwayamInSync]

This PR also adds some helpers and a new ufunc registering helper function, which will be use for register matvec and vecmat so I will make those PR after this gets merged

[ngoldbaum]

Overall looks good, a few comments below.

[ngoldbaum]

Claude points out that quad_matmul_resolve_desctriptors includes an error message that references matmul. It needs to be generalized to use the ufunc name rather than hardcode it:

numpy-quaddtype/src/csrc/umath/matmul.cpp

Lines 38 to 39 in fc52921

	"QBLAS-accelerated matmul only supports SLEEF backend. "
	"Please raise the issue at SwayamInSync/QBLAS for longdouble support");

Also because resolve_descriptors errors out for non-SLEEF backends, longdouble will never actually be able to call the naive loops. This is a pre-existing issue but it's copied here.

[ngoldbaum]

this check is unnecessary because resolve_descriptors would have already triggered the same error.

[ngoldbaum]

unaligned matmul does a different thing and calls into qblas_dot:

numpy-quaddtype/src/csrc/umath/matmul.cpp

Lines 234 to 248 in fc52921

	Sleef_quad *temp_A_buffer = new Sleef_quad[n];
	Sleef_quad *temp_B_buffer = new Sleef_quad[n];
	memcpy(temp_A_buffer, A_ptr, n * sizeof(Sleef_quad));
	memcpy(temp_B_buffer, B_ptr, n * sizeof(Sleef_quad));
	size_t incx = 1;
	size_t incy = 1;
	result = qblas_dot(n, temp_A_buffer, incx, temp_B_buffer, incy, C_ptr);
	delete[] temp_A_buffer;
	delete[] temp_B_buffer;
	break;
	}

Why the difference? Claude seems to think the matmul approach has better numerical accuracy.

[ngoldbaum]

might be worth adding a test that does vecdot on an empty array, e.g. np.vecdot(create_quad_array([]), create_quad_array([])).

[SwayamInSync]

Thanks @ngoldbaum , I was thinking to re-patch this and #88 after #95
So if possible we you can next checkout #95 and then I will easily wire the rest ones in.