Release 0.8.5

SOLVAX 0.8.5 expands reusable structured preconditioning:

• additive_tridiagonal_line_preconditioner builds a differentiable additive inverse from nonperiodic tridiagonal grid lines and an optional cyclic final axis. It is JIT-, gradient-, and variable-coefficient compatible. See Preconditioners.

• schur_projected_precond accepts an optional border-border d_block, so the projected Schur construction covers general bordered systems [[A, B], [C, D]] as well as the saddle-point case. See Preconditioners.