WorkplanCreate

Request to create a workplan from a template. OpenAPI title is ``WorkplanCreate`` (the public noun); the Python class name stays ``BlueprintCreate`` so internal imports and the DB layer are untouched.

Field	Type	Description
`template_id`required	`string (uuid)`	Source template UUID (workstream_id)
`name`required	`string`	Workplan name
`client_id`	`string (uuid) \| null`	Client UUID (optional; references platform.clients)
`config_overrides`	`object`	Configuration overrides show nested Empty object.
`schedule`	`string \| null`	Cron schedule expression (folded into configuration; null = unscheduled)
`schedule_timezone`	`string \| null`	IANA timezone for the schedule (folded into configuration)
`max_duration_minutes`	`integer \| null`	Per-instance duration guardrail in minutes (folded into configuration)
`human_checkpoints`	`any[] \| null`	Sign-off gate checkpoints (folded into configuration); [] clears the gate
`run_mode`	`string \| null`	Run posture: propose\|auto_run (folded into configuration)