pounce-cinterface 0.2.0

C ABI for POUNCE (port of Ipopt's Interfaces/IpStdCInterface.{h,cpp}). Provides IpoptCreate / IpoptSolve / IpoptFreeProblem so existing PyIpopt / cyipopt / JuMP / AMPL clients link without source changes. Phase 11 — scaffolded; full implementation lands when the algorithm-side optimizer is solving.