[DNM] Add statement-latency-bench example

[AndreiEres]

Summary

• Smoldot-based Node.js port of polkadot-sdk/substrate/client/statement-store/statement-latency-bench.
• Each virtual client runs its own smoldot light client (one libp2p peer per client). No --rpc-endpoints; bootnodes go via --bootnodes and are spliced into the chain spec.
• Full statement codec parity with lib/src/network/codec/statement.rs and sp_statement_store::Statement::encoded: sr25519 proof + priority (ts << 32) | nonce + channel + topic + data.
• Output lines mirror bench.rs so existing log parsers keep working.
• Marked DNM — depends on the statement-store example ([DNM] Add statement-store example #3143) being available in the repo and needs end-to-end testing against a real local network.

Test plan

• Start a local relay + parachain (e.g. polkadot-omni-node with --bootnodes).
• Extract relay.json and parachain.json (id=parachain, bootnodes set), as in examples/statement-chat/dev.sh.
• Run a small bench:

  node bench.js \
    --chain-spec ./parachain.json \
    --relay-chain-spec ./relay.json \
    --num-clients 4 --num-rounds 2 --messages-pattern "3:128" \
    --receive-timeout-ms 30000 --interval-ms 5000
  

  Expect Benchmark Finished: rounds_with_any_success=2 total_rounds=2 total_clients=4 and a non-empty Benchmark Results line.
• Cross-codec check: run a single JS client alongside the Rust bench.rs against the same parachain to confirm statements signed/encoded by JS are accepted by the canonical statement-store implementation.

[socket-security]

Review the following changes in direct dependencies. Learn more about Socket for GitHub.

Diff	Package	Supply Chain Security	Vulnerability	Quality	Maintenance	License
	npm/​@​polkadot/​util-crypto@​13.5.9
	npm/​@​polkadot/​keyring@​13.5.9
	npm/​@​polkadot/​util@​13.5.9

View full report

[socket-security]

All alerts resolved. Learn more about Socket for GitHub.

This PR previously contained dependency changes with security issues that have been resolved, removed, or ignored.

View full report