[Dentosal]

Makes storage cache smaller and faster.

Checklist

• Breaking changes are clearly marked as such in the PR description and changelog
• New behavior is reflected in tests
• If performance characteristic of an instruction change, update gas costs as well or make a follow-up PR for that
• The specification matches the implemented behavior (link update PR if changes are needed)

Before requesting review

• I have reviewed the code myself
• I have created follow-up issues caused by this PR and linked them here

[cursor]

PR Summary

Medium Risk
Touches core interpreter storage caching that affects hot/cold read behavior and gas determinism; while mostly a data-structure refactor, incorrect cache updates could change gas charges or storage results.

Overview
Refactors the VM storage_slot_cache from a single BTreeMap<(ContractId, Bytes32), ...> into a nested HashMap<ContractId, HashMap<Bytes32, ...>>, updating all storage read/write/clear paths to use the new grouped layout.

Updates reset_vm_state to correctly reconcile cached storage slots when applying diffs (overwrite stale cached values, convert stale present values to warm-absent None, and preserve cold-absent slots as uncached), and adjusts the diff tests accordingly. Adds a changelog entry documenting the cache change.

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