Wire burn hook-based Claude Code ingest into harness-kit

[willwashburn]

Follow-up from burn#7 (shipped in @relayburn/*@0.8.0).

What to do

Burn now exports a pure spawner primitive from @relayburn/ledger:

import { buildClaudeHookSettings, stamp } from '@relayburn/ledger';

const { sessionId, settings } = buildClaudeHookSettings();
await stamp({ sessionId }, { workflowId, agentId, persona, tier });

// Pass sessionId + settings through to the spawn args.

Extend buildInteractiveSpec at packages/harness-kit/src/harness.ts:69-153 to append --session-id and --settings when the harness is claude. The spawn site to verify against is packages/cli/src/cli.ts:579.

Acceptance

• buildInteractiveSpec({ harness: 'claude', ... }) returns args containing --session-id <uuid> and --settings <json>.
• Other harnesses (codex, opencode, etc.) are unaffected.
• Stamp metadata is applied against the pre-assigned UUID before spawn so burn attributes turns correctly.
• Smoke: workforce can spawn a Claude Code session and burn summary --since 1h shows the turn with stamped workflow/agent attribution.