feat(load-tests): add XEN-shape payload for storage-trie + account-creation stress

[niran]

Draft — alternative to #2366. Only one of these will land. This PR ships an XEN-specific payload with bundled State/Worker/Multicall contracts. #2366 instead reuses the already-deployed Simulator from base/benchmark and exposes its full config in YAML.

Summary

• Adds a xen YAML transaction type that mirrors XEN's bulkClaimRank shape: each tx loops N CREATE2 Worker deployments, and each worker writes a unique slot in an underlying State contract — N new account-trie entries plus N unique storage writes per tx, with no merging in HashedPostState.
• Bundles minimal State.sol, Worker.sol, Multicall.sol sources (with a self-contained Foundry project) and embeds their compiled bytecode as &'static [u8] constants on XenContracts. Follows the LooperPayload pattern: deploy manually, pass the addresses via YAML.
• Unblocks the xen performance-baseline scenario.

Test plan

• cargo +nightly fmt --all
• cargo +nightly clippy -p base-load-tests -p basectl --all-features (workspace-wide clippy blocked locally by an unrelated risc0 metal-kernel toolchain issue)
• cargo nextest run -p base-load-tests — 32/32 pass, including new YAML round-trip + payload tests
• End-to-end run against sepolia after forge create-ing State and Multicall

type=routine
risk=low
impact=sev5

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
base	Ignored		Apr 23, 2026 8:29pm