Epic: #2553 — Forms: Embed → hosted partner subdomain flow
Scope: Phase 0 — core handoff at app.leadtrap.ai/forms/continue?handoff=...
Shipped in: #2631 (closes #2550)
Environment: dev.leadtrap.ai (or production after deploy confirmation)
Flow under test: embed intake → server-driven OpenPageStep redirect → /forms/continue?handoff=… → behavioral wizard