Bid inclusion event PoC implementation tracker

[markolazic01]

This issue tracks competing PoCs for surfacing bid-inclusion data over SSE, either implemented within a wider-purpose event like block or as a separate event.

These PRs are supposed to help us settle on the spec, and later we might merge (only) one of them.

List View

• #9854 — extend block in place: adds block_hash + builder_index as fork-conditional fields on the existing block event.
• #9875 — new bid_included event (name not settled): emits a block (blockRootHex) field + SignedExecutionPayloadBid.
• #9876 — new included_execution_payload_bid event: same payload shape as the existing execution_payload_bid event, i.e. emits only SignedExecutionPayloadBid.
• #9896 — block_v2: new versioned event alongside block, adding block_hash + builder_index to the block event shape.

Table View

PR	Delivery	Payload	Incl. block root?
#9854	Extend block in place (fork-conditional fields)	Minimal: block_hash + builder_index	Inherent (is the block event)
#9896	New versioned block_v2 alongside block	Minimal: block_hash + builder_index	Inherent (is the block event)
#9875	Dedicated bid_included event (name TBD) - Initial Version	Minimal: block_hash + builder_index	Yes — explicit block (blockRootHex)
#9875	Dedicated bid_included event (name TBD) - New Version	Full SignedExecutionPayloadBid	Yes — explicit block (blockRootHex)
#9876	Dedicated event (included_execution_payload_bid)	Full SignedExecutionPayloadBid	No — mirrors execution_payload_bid exactly

Notes:

• Older version of feat(builder): add bid_included event #9875 is accessible by simply dropping a few commits from the new version.
• Need to make sure that the version we choose skips self built blocks, as this is not applied in each one.
• Consider handling heze.ExecutionPayloadBid depending on a chosen implementation version.