feat(miner-plan): add soft-claim adjudication using the duplicate-winner election (#4291)

[nickmopen]

Closes #4291.

Decides which of several miners claiming the same issue proceeds — by reusing the maintainer-side election (isDuplicateClusterWinnerByClaim from @jsonbored/gittensory-engine) rather than reimplementing it, so the miner and the gate agree on exactly one winner by construction. The engine module's own header earmarks this as its intended "second consumer," and the claim-ledger's comment defers exactly this adjudication to here.

What's here

• lib/claim-adjudication.js — pure adjudicateSoftClaim(self, competing). competing is the publicly-observable set of other open PRs linking the issue (the local ledger is client-side and can't see other miners). Returns:
  • isWinner — the go/no-go, driven only by isDuplicateClusterWinnerByClaim
  • winnerNumber — display-only (resolveDuplicateClusterWinnerNumber), for surfacing "you lost this claim to PR #N"
  • explicit toClaimMember bridge mapping the observed claimedAt → the engine's linkedIssueClaimedAt (the field names deliberately differ — not interchangeable by accident).
  • Fail-closed: a missing/sparse claim time loses and yields no guessed winner.
  • .d.ts + the build node --check entry.
• Tests — this miner wins / loses (winner surfaced) / no competing (trivial winner) / fail-closed sparse-timestamp cases / the field mapping.

Scope

The pure adjudication seam. Wiring it into the claim CLI (contested-claim warnings on claim list/claim claim) is the sibling claim-ledger-commands issue, per this issue's own framing.

Validation

Typecheck clean; node --check passes; full suite (npm run test):

Test Files  630 passed | 2 skipped (632)
     Tests  12527 passed | 12 skipped   (0 failed)

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.98%. Comparing base (7967e78) to head (614892e).
⚠️ Report is 34 commits behind head on main.

Additional details and impacted files

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  Coverage   93.98%   93.98%           
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  Files         406      406           
  Lines       37028    37028           
  Branches    13538    13538           
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  Hits        34801    34801           
  Misses       1570     1570           
  Partials      657      657           

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