Assets 3365 perf optimise multicall client to calculate address specific data once

[salimtb]

Explanation

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Low Risk
Pure encoding memoization with unchanged multicall targets and calldata semantics; covered by existing and new unit tests.

Overview
MulticallClient now caches ABI-encoded balanceOf and getEthBalance calldata per account address (case-normalized), because that payload only depends on the account, not the token contract target.

Batch aggregate3 construction moves into buildAggregate3BalanceCalls, which pulls cached encodings instead of re-encoding for every token row. The single-call ERC-20 fallback path uses the same cache.

A test asserts encodeFunctionData runs once per distinct account for each method type in a batch, and that counts stay flat on a second batch with the same accounts (cache reuse). Changelog updated under Unreleased.

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