feat(tests): pin gas growth and forwarding after repayment in eip-8037

[spencer-tb]

Description

Stacked follow-up to #3478. Until #3478 merges, GitHub also shows the parent PR's commits; the intended follow-up diff is commit a69796202a.

Add two focused EIP-8037 gas-observability pins:

• a same-frame control proving that a local state-gas refill can already make the second of two GAS readings larger than the first; and
• an exact EIP-150 boundary proving that gas repaid at a successful child merge participates in the next call's 63/64 forwarding base.

The forwarding test derives the smallest sufficient base from fork metadata. Without merge-time repayment the child is one gas below that boundary and reverts its marker; with repayment it completes.

This PR remains draft until ethereum/EIPs#12265 is stacked on ethereum/EIPs#12256 and ref_spec_8037.version can be updated to the final combined EIP revision rather than an intermediate SHA.

Related Issues or PRs

• feat(spec-specs, tests): repay spilled state gas from the reservoir when a child merges #3478
• Update EIP-8037: restore a frame's state-gas on rollback EIPs#12256
• Update EIP-8037: return state-gas to gas_left when a child merges EIPs#12265

Checklist

• Ran fast static checks to avoid CI fails, see Code Standards & Verifying Changes: just static
• PR title has the form <type>(<area>): <title>, where <type> and <area> come from an appropriate C-<type>, respectively A-<area>, label. The title should match the target squash commit message.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.01%. Comparing base (b462ba2) to head (a697962).
⚠️ Report is 1 commits behind head on forks/amsterdam.

Additional details and impacted files

@@               Coverage Diff                @@
##           forks/amsterdam    #3519   +/-   ##
================================================
  Coverage            94.01%   94.01%           
================================================
  Files                  624      624           
  Lines                36905    36912    +7     
  Branches              3326     3326           
================================================
+ Hits                 34695    34702    +7     
  Misses                1533     1533           
  Partials               677      677           

Flag	Coverage Δ
unittests	94.01% <100.00%> (+<0.01%)	⬆️

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[spencer-tb]

Superseded by #3478. The validated coverage commit has been appended to the existing PR.