Accelerate finite proof certificates for v0.3.5

[Polarnova]

Summary

• replace the materialized normalized-classification search with a pruned, cost-balanced single-file fold
• validate generated candidates through inverse-matrix sidecar certificates while preserving the existing candidate API
• streamline the reader-facing README and prepare package version 0.3.5

Local validation

• generated candidate reproduction check
• forbidden-token and diff audits
• changed certificate modules compile
• complete normalized classification: 165.37 s, 6.91 GB peak
• largest 32-leaf certificate bucket: 13.11 s