refactor: simplify registry verification for Node 22

[steipete]

What Problem This Solves

The registry verifier retained a manual cancellation fallback for runtimes older than the declared Node 22 floor, plus multi-package processing after an earlier parser already restricted both fields to one package claim.

Why This Change Was Made

Use native AbortSignal.any and Node timer handles, remove the encoding wrapper, and verify the single matching claim directly. Keep the conservative publication policy and existing diagnostic strings unchanged. Trim comments that duplicated the implementation or documentation.

User Impact

No behavior, CLI contract, or runtime-floor change.

Evidence

• pnpm typecheck, pnpm lint, pnpm test src/registry-verifier.test.ts src/review-validation.test.ts, and pnpm build passed (61 tests).
• Isolated Codex autoreview is scoped-clean at P0–P2. An initial diff-only pass lacked the unchanged claim-parser definition; a full-source/context pass verified its single-package invariant.
• Live compiled-runtime proof: ran dist/registry-verifier.js against a real local HTTP server. A matching published manifest dropped the finding; caller abort and a 25 ms deadline both returned unknown and kept findings. No mocked fetch implementation was used.

[clawsweeper]

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Pull request received. I will update this pull request when review starts.

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[clawsweeper]

ClawSweeper status: review started.

I am starting a fresh review of this pull request: refactor: simplify registry verification for Node 22 This is item 1/1 in the current shard. Shard 0/1.

This placeholder means the worker is alive and reading the current context. I will edit this same comment with the actual review when the claws are done clicking.

Crustacean status: shell secured, claws on keyboard, evidence pebbles being sorted.