subagenttasks

Refactor sales-agent's third-party cost tracking to cross-post into subagenttasks.com instead of only the local finance queue

cwc-sales currently writes third-party cost tracking into cowork's local finance.jsonl queue only. Refactor to also POST a durable task row to subagenttasks.com tagged source_site='sales-agent', so cost-relevant outreach work is visible fleet-wide, not just in the local mailbox.