Define recursive EIP-8025 execution proof guest

[frisitano]

Summary

• introduce recursive execution-proof public inputs with immutable origin and advancing head checkpoints
• define the guest private input, authenticated beacon lineage, recursive verification, and stateless execution transition
• simplify the Proof Engine to proof verification and generation, removing payload and fork-choice notifications
• keep execution-proof propagation gossip-only while retaining eproof peering discovery

Design notes

• proofs are produced for full beacon blocks; intervening produced empty blocks are authenticated through the bid lineage, while missed slots require no witness
• guest verification of bid and envelope BLS signatures remains a TODO; consensus clients retain the normal Gloas signature and state-dependent checks

Validation

• make lint
• make test fork=eip8025 (1366 passed, 6432 skipped)

[jtraglia]

Other than the mismatched tense here, something about this sentence is a bit awkward to read. I would suggest splitting it up into two+ sentences as it's pretty long.

Suggested change

	from the arguments. A typed implementation invokes
	`verify_stateless_new_payload` directly. A serialized zkVM implementation MAY
	invoke `run_stateless_guest`, decodes its output, and MUST check that the
	returned `new_payload_request_root` equals `compute_new_payload_request_root`
	for the constructed input before exposing the result. In both cases the logical
	from the arguments. A typed implementation invokes
	`verify_stateless_new_payload` directly. A serialized zkVM implementation MAY
	invoke `run_stateless_guest`, decode its output, and MUST check that the
	returned `new_payload_request_root` equals `compute_new_payload_request_root`
	for the constructed input before exposing the result. In both cases the logical

[frisitano]

Yep, agreed, I expect much of the prose will change in this PR. I'll mark the PR as ready for review when I have things in a better state.

[jtraglia]

Yep, just did a quick skim & wanted to mention this 😅 I'll do an in-depth review when its marked as ready.

[frisitano]

That's appreciated. I just don't want you wasting your time reviewing trash 🤣

[jtraglia]

Since Gloas gossip validation specs are now executable functions, it might be worth converting these to executable functions now too. Not sure if you'd want to handle this here or in a separate PR. Since it's just a single new gossip topic, I think it would be alright to do it in this PR. And no need to worry about tests.

[frisitano]

Very nice addition to the specs! Yep, let's get it done in this PR