test: add EIP-7702 delegation transaction tests for pending state (#281)

* test: add EIP-7702 delegation transaction tests for
  pending state

  Add tests for EIP-7702 authorization and delegation transactions in
   pending/flashblocks state per #279.

  Tests:
  - Single delegation in pending flashblock
  - Multiple delegations in same flashblock
  - Receipt retrieval for EIP-7702 transactions
  - Delegation followed by execution across flashblocks

  test_eip7702_delegation_then_execution fails with overflow at
  state.rs:558 - this surfaces the sporadic behavior users reported.

  Closes #279

* fix: prevent overflow in flashblock gas calculation

Use saturating_sub instead of subtraction when calculating per-transaction
gas from cumulative gas values. When multiple flashblocks belong to the
same block, subsequent flashblocks may have lower cumulative gas values
than earlier ones, causing an arithmetic underflow.

Fixes #279

* fix(rpc): cumulative gas tracking

* chore: rebase

* fix: remove unnecessary saturating_sub from gas calculation

test data was the issue, not the subtraction. cumulative gas values are monotonically increasing so this should never underflow

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Co-authored-by: Andreas Bigger <[email protected]>
Co-authored-by: Haardik <[email protected]>

Author: 3 people