pv: Go binding scanner and generators (blocks 100% provable-contract coverage for Go course repos) #5408

A Go module with a language-neutral pv contract reaches only L2 in pv proof-status (0/3 bindings: verify-bindings/infer scan Rust pub fn only), and pmat comply CB-1308 (verification ladder, wants L5) therefore fails on any Go repo. Need: (1) a binding scanner for Go func (exported identifiers) so pv lint gates 20/reverse-coverage arm; (2) generators for Go asserts/tests/native fuzz targets. Spec reference: rmedia#1079 (TSS-001 §Tooling gaps, decided: Go first). Repro: a small Go module with one contract under contracts/, run pv proof-status contracts and pmat comply check --failures-only. Until then the Go course repo runs comply as a nightly lab check only, with the contract line enforced at runtime by tests.