pounce-linsol 0.10.0

Symmetric linear-solver trait layer for POUNCE (port of Ipopt's Algorithm/LinearSolvers/Ip{SymLinearSolver,SparseSymLinearSolverInterface,TSymLinearSolver,TSymScalingMethod,TripletToCSRConverter}). No FFI; concrete backends are pounce-feral (the pure-Rust sparse LDLᵀ default) and the optional pounce-hsl (MA57).