Add deterministic worker idle waiting

[ggoodman]

What

• Add LedgerWorkers.waitForIdle({ signal }).
• Resolve at an idle linearization point when no pending, delayed, leased, or executing work remains.
• Share one generation-based change signal between event following and worker-state waiting.
• Supervise dispatch and work-processing failures through one worker failure state that preserves arbitrary rejection reasons and lease ownership.
• Make event-stream and worker-idle reads stop waiting promptly on cancellation while safely observing the underlying storage operation.

Why

Consumers can coordinate with Sledge's worker runtime without polling ledger projections in user space. The shared internal primitives close read/subscribe races once, keep cancellation behavior consistent across consumers, and leave durable state authoritative.

Checks

• node --run lint
• node --run typecheck
• node --run test — 132 passing
• node --run build
• npm pack --dry-run

[ggoodman]

@codex review

[chatgpt-codex-connector]

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Reviewed commit: 5546c7b358

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[ggoodman]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 4ac3e39dcf

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[ggoodman]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. 👍

Reviewed commit: 2b00f64fff

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

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• Mark a draft as ready
• Comment "@codex review".

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