fix(specs,tests): check SSTORE access cost before the implicit read

[nerolation]

🗒️ Description

EIP-7928 pre-state validation for SSTORE requires the slot's access cost to be covered, in addition to the EIP-2200 stipend sentry, before the implicit read of the current storage value. Since EIP-8038 raised COLD_STORAGE_ACCESS (3000) above CALL_STIPEND (2300), the sentry alone no longer implies the access cost is covered: a cold SSTORE in a frame with 2301–2999 gas passed the sentry, performed the implicit read, and recorded the slot in the block access list before failing in charge_gas. Storage reads survive frame rollback by design, so the unaffordable slot ended up in the BAL and its hash.

This PR checks the cold/warm access cost before the implicit read in the Amsterdam SSTORE, so such a slot is neither read nor recorded. Gas usage, refunds, and post-state are unchanged: the frame runs out of gas either way. The BAL is the only observable difference.

Test changes in test_bal_sstore_and_oog:

• oog_at_eip2200_stipend_plus_1 now expects no BAL entry, previously expected a storage read.
• New oog_at_cold_access_cost_minus_1 case: no BAL entry.
• New oog_at_cold_access_cost case: storage read in BAL, implicit SLOAD done, OOG on the write cost.

🔗 Related Issues or PRs

EIP-7928 wording update here.

✅ Checklist

• All: Ran fast static checks to avoid unnecessary CI fails, see also Code Standards and Verifying Changes.

• All: PR title has the form <type>(<area>):, where <type> and <area> come from an appropriate C-<type> and A-<area> label. The title should match the target squash commit message.

• All: Considered updating the online docs in the [./docs/](/ethereum/execution-specs/blob/HEAD/docs/) directory.

• All: Set appropriate labels for the changes, only maintainers can apply labels.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.30%. Comparing base (b548afb) to head (8f58985).
⚠️ Report is 1 commits behind head on forks/amsterdam.

Additional details and impacted files

@@               Coverage Diff                @@
##           forks/amsterdam    #3111   +/-   ##
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  Coverage            93.30%   93.30%           
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  Files                  624      624           
  Lines                36986    36987    +1     
  Branches              3383     3383           
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+ Hits                 34511    34512    +1     
  Misses                1693     1693           
  Partials               782      782           

Flag	Coverage Δ
unittests	93.30% <100.00%> (+<0.01%)	⬆️

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[nerolation]

Close in favor of #3064