fix(consensus): run full pre-execution validation

[fakedev9999]

What

• Replace the partial body check with Reth's full pre-execution block validation.
• Add a regression test for a Cancun block whose header blob gas does not match its body.

Why

Fork-specific pre-execution invariants must be checked before executing a block in the guest.

Validation

• cargo test -p rsp-client-executor
• cargo check --all --all-targets
• cargo clippy --all --all-targets -- -D warnings
• cargo +nightly fmt --all -- --check
• cargo tree
• (cd bin/client && cargo tree)

[github-actions]

Block 20600000	Base Branch	Current PR	Diff	Diff (%)
Total Cycle Count	282,133,886	282,138,174	4,288	0.00
Inputs deserialization	72,433,233	72,432,440	-793	-0.00
Initialize Witness DB	61,250,381	61,249,984	-397	-0.00
Recover Senders	7,944,806	7,944,806	0	0.00
Header Validation	1,404,771	1,406,641	1,870	0.13
Block Execution	84,329,526	84,329,283	-243	-0.00
Block Validation	3,983,009	3,982,242	-767	-0.02
State Root Computation	32,845,348	32,845,309	-39	-0.00
Syscall Count	208,720	208,720	0	0.00
Prover Gas	350,711,511	350,714,715	3,204	0.00