Implement ADR-0026 beta readiness remediation

[satran004]

Summary

Implements the ADR-0026 P0 beta-readiness remediation pass for ZeroJ.

This PR hardens BBS secret handling, fixes the gnark negative e2e path, pins PlonK on-chain protocol constants, promotes a TxOutRef-bound Groth16 validator into main sources, updates the Yaci e2e harness for the known DevKit BLS-costing issue, and documents the remaining production gates.

Key Changes

• Add ADR-0026 production-readiness review and remediation plan.
• Redact BbsSecretKey / BbsKeyPair toString() output.
• Route hidden BBS signature.e() multiplication through the secret-scalar provider path.
• Add BBS raw proof-size/message-count caps.
• Fix gnark sealed-bid negative e2e test to expect proof-generation failure.
• Pin PlonK on-chain fr, G1 generator, and G2 generator checks.
• Add negative VM tests for tampered PlonK protocol constants.
• Add Groth16BLS12381TxOutRefBindingVerifier in main sources.
• Add replay-rejection VM test for TxOutRef-bound Groth16 verification.
• Harden Yaci e2e tests to skip only the known DevKit blstJNI BLS-costing failure.
• Add GraalVM JNI/resource metadata for zeroj-blst.
• Correct zeroj-blst docs from FFM to JNI/SWIG.
• Update docs and README status language for beta/testnet vs production/value-bearing use.