BUG: Preserve object common-dtype promotion in Quad ufuncs

[SwayamInSync]

Closes #114

The promoters now preserve NumPy's ObjectDType precedence. When a Quad ufunc receives an object-array input, it selects NumPy's existing object loop rather than forcing the object operand to Quad.

This applies in both operand orders and covers:

• Arithmetic ufuncs such as add and multiply
• Comparisons with Boolean output
• Logical operations with the object output used by NumPy's object loops
• matmul
• Broadcasting and masked out= operations
• Both SLEEF and long-double backends

Operations without an applicable object loop continue to raise normally. Unsupported Quad/complex and Quad/string promotion is unchanged, and importing quaddtype does not affect built-in-only NumPy dispatch.

The change also makes matmul promoter registration failures propagate instead of being silently cleared.

[SwayamInSync]

This is small addition but important to ensure we do not override NumPy's default