feat: harden portable evolution

[EvanProgramming]

Summary

• bind learned guidance to its proven provider/model unless cross-model replay validates it
• score verifier reliability and prioritize high-value background reviews
• add a read-only learning constitution and harness-neutral experience capsule export/import
• expose task-family learning curves while keeping imports inactive

Security

• constitution has no model/API write path
• secret-like capsules are rejected and imported capsules never activate
• provider/model mismatch fails closed to revalidation

Validation

• make check
• KYROZEN_DB_PATH=/state.sqlite3 make test (51 tests)
• capsule round-trip and constitution smoke
• benchmark replay tests
• git diff --check