pounce-linsol 0.5.0

Symmetric linear-solver trait layer for POUNCE (port of Ipopt's Algorithm/LinearSolvers/Ip{SymLinearSolver,SparseSymLinearSolverInterface,TSymLinearSolver,TSymScalingMethod,TripletToCSRConverter}). No FFI; concrete backends live in pounce-hsl, pounce-mumps (future), pounce-feral (future).