Function solve_with_solver 

pub fn solve_with_solver(
    eph: &dyn EphemerisSource,
    inputs: &SolveInputs,
    with_geodetic: bool,
    solver: SolverRecipe,
) -> Result<ReceiverSolution, SppError>

SPP solve with an explicit SolverRecipe for the trust-region stage.

Selecting SolverRecipe::NalgebraTrfLegacy is bit-identical to solve. SolverRecipe::OwnedDeterministicTrf swaps in the owned deterministic Gaussian-elimination factorization for the dense trust-region subproblem (no nalgebra LU, no black-box BLAS in that solve), pinned to its own frozen-bits golden; all other model stages are unchanged. The owned kernel owns ONLY the subproblem factorization: the normal-matrix / gradient / norm reductions that build the subproblem still go through nalgebra’s CPU-dispatched dense algebra, so the cross-platform bit guarantee is scoped to the factorization (the converged bits are this build’s reproducible output, not a portable constant).