Invoke Human Tasks

One-call posting path: create an Invoke human task from title, description, reward_cents, contact_email, and optional category. The poster's first task is published immediately with status=open, fee_waived=true, platform_fee_cents=0, and task_url. Later posts return pending_payment plus checkout_url

Alias for post_task: first task posts immediately with a waived fee; later tasks return the pending task id plus checkout URL for activation.

Alias for post_task: hire a human through Invoke. First task posts immediately with a waived fee; later tasks return pending_payment plus checkout_url/payment_url.