Add SWI 0x09 and 0x0a as original ARM routines. Evaluate the fixed-point angle polynomial with wrapped products, reduce ArcTan2 ratios with integer division, and handle axes and quadrants. Require sign-extended 16-bit inputs and preserve non-result caller registers.
Add 15 regression tests for fixed-point and floating-point references, signed limits, rounding, quadrant boundaries, caller flags, stack bounds, repeated calls, and DMA/IRQ progress. Validate 671 default and 660 core-only tests in debug and release, plus all 10 native Darwin ARM64 window smoke tests.
