v2.0.0: Replace CORDIC rotation with polynomial evaluation

[GeEom]

Polynomial evaluation replaces CORDIC rotation mode for all forward functions

New evaluation strategy:

• sin/cos: Minimax (Chebyshev) polynomials via Horner's method, with range reduction to avoid
  cancellation near π/2
• sinh/cosh: Factored Taylor series (degree 9–14 depending on precision), replacing the CORDIC rotation +
  Taylor hybrid
• exp: Factored Taylor series (degree 7–12) with single-step argument reduction, replacing the iterative
  reduction + sinh_cosh path
• New chebyshev table module with Remez-generated coefficients and horner() evaluator

Removed public API (breaking):

• cordic_scale_factor(), hyperbolic_gain(), hyperbolic_gain_inv()
• circular_rotation(), hyperbolic_rotation()
• CordicNumber::from_i2f62()
• CIRCULAR_GAIN_INV, HYPERBOLIC_GAIN, HYPERBOLIC_GAIN_INV constants

Accuracy improvements:

• tan: 2.8× mean, 4.7× median (I32F32)
• sinh/cosh: ~7× mean, ~2.3× median (I32F32)
• tanh: 7.3× mean (I32F32); coth: 2.8× mean (I32F32)
• exp/pow2 median improves ~1.3–2.2×

Saturation threshold changes:

• exp positive: 22.2 → 10.4 (I16F16), 44.4 → 21.5 (I32F32)
• exp negative: -9.2 → -11.1 (I16F16), -16.2 → -22.2 (I32F32)
• pow2 negative: -13.2 → -16.1 (I16F16), -23.3 → -32.1 (I32F32)
• sinh/cosh saturation: 10.4 → 11.1 (I16F16), 21.5 → 22.2 (I32F32)

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

❌ Patch coverage is 98.87640% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/ops/exponential.rs	96.55%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!