Public Conversation Sharing with Authenticated Fork-to-Continue

[avishek0769]

Summary

Add shareable chat links so others can read conversation history publicly and optionally continue by creating their own copy after login.

Problem

There is no mechanism to share a chat transcript externally. Collaboration and debugging workflows are blocked.

Expected Solution

Create a share token/slug for a chat. Public route should show conversation history in read-only mode without auth. If visitor wants to continue chatting, require authentication and create a new chat copy for that user so original owner data is unaffected.

Scope

• Backend:
  • backend/prisma/schema.prisma (share metadata/entities)
  • backend/controllers/chat.controller.js
  • backend/controllers/chatMessage.controller.js
  • New routes/controller(s) for share read/fork
• Frontend:
  • src/pages/ChatPage.tsx
  • New public shared-chat page
  • src/lib/api.ts

Acceptance Criteria

• Owner can generate and revoke a share link.
• Unauthenticated users can view shared conversation read-only.
• “Continue this chat” requires auth and creates a new chat under current user.
• New chat copy has conversation history but does not mutate original chat/messages.

Notes

Consider optional controls: expiry, one-click revoke, and private/unlisted mode.