feat(builder): publish stateless payload envelopes

[krisoshea-eth]

Motivation

The Builder needs a small safety boundary between exact envelope assembly and later reveal timing/runtime wiring. Once a local selection is verified, the envelope must be signed and submitted at most once without allowing a conflicting payload for the same Beacon block root.

Description

This draft adds an EnvelopePublisher that:

• accepts complete stateless envelope material;
• requires the local Builder index and an exact recorded selection;
• signs through BuilderSigner;
• reserves the exact unsigned envelope root before the network outcome becomes ambiguous;
• submits the envelope with blobs and KZG proofs;
• explicitly requests consensus_and_equivocation validation;
• marks publication only after the Beacon Node accepts it;
• coalesces concurrent exact attempts and permits a later exact retry after rejection; and
• rejects changed envelope content for the same selecting block root.

The selection lookup is injected, so this PR does not choose an SSE contract, payload-store implementation, cutoff, retry policy, metrics, or runtime wiring.

Dependencies

This draft is stacked on #9975 for BidLedger. The review surface added here is two files:

• packages/builder/src/services/envelopePublisher.ts
• packages/builder/test/unit/services/envelopePublisher.test.ts

Validation

• 9 focused envelope-publication tests
• 19 inherited BidLedger tests, including reveal reservation and publication state
• Builder type-check
• Biome check
• git diff --check

The Builder build and import check was validated before the ledger-only parent refresh.

Tracks LOD-67.

Review plan

Treat #9980, #9981, and #9982 as one logical selection and reveal path. Keep this draft isolated during development, but combine the services around their first runtime consumer if maintainers prefer fewer service-only PRs.

This PR was written primarily with Codex. I reviewed the implementation and validated the focused and package-level checks listed above.