feat: persist resumable audit runs and queue explicit idempotent GitHub sync

[bearmug]

Audit baseline: aa595438650cfbaa6db310792929c6219cc003b2 (origin/main at audit start).

Problem

Long audits and subagent fan-outs can finish useful local work while connectivity or GitHub authentication is unavailable. There is no durable audit run ledger, resumable work graph, or local issue outbox, so a terminal/network interruption risks lost work or duplicate external writes.

This is related to future Forge lifecycle #102 but is not duplicate: #102 does not specify offline checkpoints, queued GitHub drafts, idempotent reconnect sync, or ambiguity-after-timeout handling.

Proposed MVP

Persist a versioned run directory keyed by repository and run ID containing:

• baseline SHA/repository/phase/status and last checkpoint;
• stable work-item IDs, inputs, dependencies, attempts, output artifact paths/hashes;
• normalized finding IDs and dedupe evidence;
• GitHub issue drafts with idempotency key, draft|pending|synced|conflict|failed, attempts, last error, and resulting issue number/URL.

Use atomic local writes. Resume skips completed work with matching hashes and reruns only incomplete/invalidated items.

Expose explicit status/resume/sync actions. Sync must be user-invoked after network/auth returns, query stored numbers/idempotency markers before creation, mark ambiguous already-created issues as synced, and stop on conflicts.

Safety / non-goals

• No hidden background GitHub writes or auto-sync merely on reconnect.
• No credentials/tokens in run state.
• No push, merge, release, tag, or npm publish behavior.
• Existing approval requirements remain in force.

Acceptance criteria

• Kill/restart resumes a multi-work-item audit without rerunning completed items.
• Offline/auth failure leaves inspectable drafts and loses no findings.
• Repeated explicit sync after timeout creates at most one issue per idempotency key.
• Conflicts and permanent auth failures remain queued with actionable status.
• Fake-adapter tests cover offline, timeout-after-create, reconnect, duplicate, conflict, and interrupted sync.