feat: add recursive execution proof guest logic

[frisitano]

Summary

• add a shared recursive execution-proof guest crate and canonical recursive input/state types
• align Gloas new-payload request structures with Lighthouse progressive SSZ commitments
• integrate the recursive adapter with both the Reth and Ethrex stateless validator paths
• add focused invariant, failure-path, and native client-adapter coverage

Testing

• cargo test -p recursive-execution-proof --offline
• cargo test -p stateless-validator-reth --test host_execution --features host --offline
• cargo test -p stateless-validator-ethrex --test host_execution --features host --offline

Deferred boundaries

• prior-proof verification remains proof-system specific through ExecutionProofVerifier
• bid and envelope BLS signature verification remains at the consensus-client boundary