v0.2.0

Changed

• Breaking: golub_welsch() now returns Result, propagating QL non-convergence as QuadratureError::InvalidInput instead of silently returning inaccurate nodes/weights. All internal compute_* functions in gauss_jacobi, gauss_laguerre, gauss_hermite, and gauss_radau propagate accordingly. Public constructors already returned Result, so most callers are unaffected.
• Breaking: GaussLobatto::new(0) now returns QuadratureError::ZeroOrder (previously InvalidInput). GaussLobatto::new(1) still returns InvalidInput.
• Input validation for tanh_sinh, oscillatory, cauchy_pv, and cubature::adaptive now rejects ±Inf bounds (not just NaN). Error variant is unchanged (DegenerateInterval).
• CubatureRule::new assertion promoted from debug_assert_eq! to assert_eq!.
• Tanh-sinh non-convergence error estimate now uses the difference between the last two level estimates instead of a fabricated tol * 10 value.
• QUADPACK error estimation heuristic in gauss_kronrod documented as an intentional simplification of the full formula.

Fixed

• ln_gamma reflection formula: .sin().ln() → .sin().abs().ln() prevents NaN for negative arguments where sin(π·x) is negative (affects Gauss-Jacobi with certain α, β near negative integers).
• Newton iteration in Gauss-Lobatto interior node computation now clamps iterates to (-1+ε, 1-ε), preventing division by zero in the P'' formula when an iterate lands on ±1.
• partial_cmp().unwrap() in golub_welsch and gauss_lobatto sort replaced with .unwrap_or(Ordering::Equal) to avoid panics on NaN nodes.
• Adaptive cubature global_error subtraction clamped to max(0.0) to prevent negative error estimates from floating-point cancellation.

Added

• Dimension cap (d ≤ 30) for adaptive cubature — returns InvalidInput for higher dimensions where Genz-Malik's 2^d vertex evaluations would be impractical.
• New tests: infinity rejection (tanh-sinh, oscillatory, Cauchy PV, cubature), dimension cap, Lobatto error variant splitting, tanh-sinh non-fabricated error, Jacobi negative α/β exercising the reflection path.