refactor(evm): encode state root without using bincode

[oXtxNt9U]

Summary

Compute the state root from an explicitly defined byte encoding instead of bincode, so the hash no longer depends on revm serialization details that could silently change across dependency upgrades.

Checklist

• Documentation (if necessary)
• Tests (if necessary)
• Ready to be merged

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.70%. Comparing base (d2844bb) to head (33614ce).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1475      +/-   ##
===========================================
+ Coverage    78.05%   78.70%   +0.64%     
===========================================
  Files          953      964      +11     
  Lines        16312    16958     +646     
  Branches      2350     2424      +74     
===========================================
+ Hits         12733    13346     +613     
- Misses        3574     3605      +31     
- Partials         5        7       +2     

Flag	Coverage Δ
contracts	91.76% <ø> (?)
packages	78.35% <100.00%> (+0.29%)	⬆️

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