pounce-cinterface 0.4.0

C ABI for POUNCE (port of Ipopt's Interfaces/IpStdCInterface.{h,cpp}). Provides CreateIpoptProblem / IpoptSolve / FreeIpoptProblem so existing PyIpopt / cyipopt / JuMP / AMPL clients link without source changes. Feature-complete for the upstream Ipopt C ABI surface.