chore(specs, tests): restore spilled state gas to reservoir on revert/halt

[spencer-tb]

🗒️ Description

When a child frame's state gas spills from the reservoir into gas_left and then reverts or halts, the spilled state gas was lost. Since state changes are rolled back, all state gas (reservoir + spill) should be restored to the parent's reservoir, not just the original reservoir.

🔗 Related Issues or PRs

N/A.

✅ Checklist

• All: Ran fast tox checks to avoid unnecessary CI fails, see also Code Standards and Enabling Pre-commit Checks:

  uvx tox -e static

• All: PR title adheres to the repo standard - it will be used as the squash commit message and should start type(scope):.
• All: Considered updating the online docs in the ./docs/ directory.
• All: Set appropriate labels for the changes (only maintainers can apply labels).

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Additional details and impacted files

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[jwasinger]

Isn't the state gas spent by a frame not refunded in the case of revert? From the EIP:

State gas charged for account creation (CREATE, CALL to new account, and EOA delegation) is consumed even if the frame reverts — state changes are rolled back but gas is not refunded.

I'm guessing that this also applies to SSTORE as well:

Refunds use refund_counter rather than direct gas accounting decrements, so that reverted frames do not benefit from the refund.

[spencer-tb]

Thx @jwasinger. Comments below!

These two EIP quotes are about different items compared to what the PR changes. What this PR changes:

• When a child frame's state gas spills from the reservoir into gas_left and then reverts/halts, the spilled portion was previously lost. The update restores child_evm.state_gas_used + child_evm.state_gas_left (the full forwarded amount) instead of only the original reservoir.
• This now matches the updated EIP: "On child revert or exceptional halt, all state gas consumed by the child, both from the reservoir and any that spilled into gas_left, is restored to the parent's reservoir."