Start Onboarding
Collect required onboarding start fields and submit to POST /api/onboarding/start.
Tenant ID (or leave blank and provide proposed slug)
Proposed Slug (used as tenant_id if tenant_id is blank)
Tenant Type
Signup Event ID
Business Name
Contact Name
Assistant Name Preference
User Name Preference
Preferred Channel
Backup Channel
Owner User ID
Start Onboarding