Collection forms and public submission pages

[arferreira]

Public-facing forms that let users collect testimonials from their customers without requiring auth.

What's needed

Backend:

• forms DB entity and migrations (see architecture doc for schema — headline, description, questions JSONB, branding fields, thank you page config)
• Forms CRUD under /api/v1/projects/{id}/forms
• Public submission endpoint POST /api/v1/public/forms/{slug}/submit (no auth)
• Public form page GET /f/{slug} (serves the form)

Frontend:

• Form builder page in dashboard (create/edit forms per project)
• Public form page rendered by the dashboard or server-side

Context

This is the primary way users collect testimonials. Without forms, testimonials can only be added manually through the API. The form system is the core value prop — "give someone a link, get a testimonial back."

Part of v0.1 milestone.