Epic 10: Viral loop (Invites & soft profiles)

[Tar-ive]

Reshaped from docs/user-stories.md. Legend: ✅ Live · 🟡 Partial · ⚪ Planned.

Personas: Giver, Guest

• 10.1 Share a gift challenge 🟡 — As a Giver, I want to share a swipe challenge, so that I learn a friend's taste in a fun way.
  • /feed/swipe multi-channel share sheet; link carries senderId when signed in.
• 10.2 Complete a challenge with no signup 🟡 — As a Guest, I want to complete an invite without an account, so that there's zero friction.
  • /invite/[code]: welcome → consent → swipe → birthday → done → /feed, creating a local soft profile.
• 10.3 Get notified when a friend responds 🟡 — As a Giver, I want to know when someone finishes my challenge, so that I can act on their taste.
  • Guest creates a connection for the sender; shown in /feed/activity. Live only after the connections backend deploy.