chore(deps): update Lighthouse for stateless Gloas production

[shane-moore]

Merge order: #1311 → #1312 → #1313. All three target epbs; rebase remaining branches after each merge.

Problem, Evidence, and Context (Required)

First of three PRs for #1309. SIP-94 needs Anchor to receive the local payload root before proposer consensus; sigp/lighthouse#10036 supplies that integration and stateless-production configuration.

Change Overview (Required)

• Pin Lighthouse to 12802d0d1750e0a94c3ba32ae6673a1c2ce21260 and update the lockfile.
• Adapt the signing interface and test callers. Stateless production remains disabled and the existing envelope flow remains active in this layer.
• Target epbs; the collector preparation and protocol activation follow separately.

Risks, Trade-offs, and Mitigations (Required)

The dependency revision comes from an unmerged Lighthouse PR. Keeping protocol activation separate makes the dependency adaptation independently reviewable. The final activation must retain the exact block and envelope ownership checks from that revision.

Validation (Required)

• cargo check --workspace --tests: passed on this layer.
• cargo fmt --all -- --check: passed on this layer.
• The complete stack also passes workspace lint, 522 affected-crate tests, and make test (987 passed). Those results cover the integrated stack, not this layer alone.

Rollback (Required for behavior or runtime changes; optional otherwise)

Revert this dependency and adapter change before the later layers land. Once they land, revert dependents first.

Blockers / Dependencies (Optional)

Depends on sigp/lighthouse#10036 being accepted, or an explicit decision to carry its revision. All stack branches live in shane-moore/anchor.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (epbs@58e2255). Learn more about missing BASE report.

Additional details and impacted files

@@           Coverage Diff           @@
##             epbs    #1311   +/-   ##
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  Coverage        ?   80.98%           
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  Files           ?      181           
  Lines           ?    42064           
  Branches        ?        0           
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  Hits            ?    34065           
  Misses          ?     7999           
  Partials        ?        0           

Flag	Coverage Δ
rust	80.98% <100.00%> (?)

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[shane-moore]

Reviewed 6a9037c8. No findings.

The Lighthouse pins and lockfile move together, and the signing adapter keeps stateless production disabled. When consensus selects another operator’s block, Lighthouse now skips fetching the losing local envelope. Anchor already starts the non-builder signing task inside sign_block, so that path remains intact.

Verified hosted debug and release logs: 1,020 tests passed in each on the same source tree as this head, including the relevant envelope-signing tests. Local-testnet CI also passed. Lighthouse #10036 has merged.

Scope: this dependency and adapter layer only.

Reviewed by gpt-6 astra high.