refactor(types): share HTTP commit certificate JSON types across evm-node and consensus

[crazywriter1]

Follow-up to #40 (re-opened after main was force-pushed and GitHub auto-closed the previous PR).

Summary

Introduces arc_consensus_types::commit_http with HttpCommitCertificate / HttpCommitSignature and try_into_commit_certificate() so the execution RPC (get_certificate) and consensus RPC sync paths deserialize the same JSON shape without duplicated structs.

Motivation

The wire format (height, round, block_hash, base64-encoded signature bytes) lived in two places, which risks drift and inconsistent handling. One shared module keeps JSON alignment between arc-evm-node and arc-node-consensus.

Changes

• Add crates/types/src/commit_http.rs and pub mod commit_http in arc-consensus-types.
• Add serde_with (with base64) to arc-consensus-types; update Cargo.lock.
• arc-evm-node: re-export RpcCommitCertificate from HttpCommitCertificate; remove duplicate local types.
• arc-node-consensus: deserialize via HttpCommitCertificate in RPC sync; use try_into_commit_certificate().
• malachite-app HTTP RpcCommitCertificate uses Vec<HttpCommitSignature> for signatures (serialization unchanged).

Testing

• cargo test -p arc-consensus-types
• cargo test -p arc-evm-node get_certificate
• cargo test -p arc-node-consensus (use OPENSSL_NO_VENDOR=1 if vendored OpenSSL build fails locally)
• cargo clippy -p arc-consensus-types -p arc-node-consensus -p arc-evm-node --all-targets -- -D warnings

[crazywriter1]

Hi @ZhiyuCircle following up on #40: I rebased onto the latest main and opened this PR with the same change set. Could you take a look when you have a moment? Thanks again for the guidance.