docs: update documentation for QR code check-in system

docs/SESSION_CONTEXT.md

@@ -23,7 +23,7 @@
 - ✅ Docker Compose (nginx:8080 + frontend + backend + PostgreSQL)
 - ✅ All frontend views with real API integration
 - ✅ Backend API (Node.js + Express)
-- ✅ PostgreSQL database with 7 tables (Prisma ORM)
+- ✅ PostgreSQL database with 8 tables (Prisma ORM)
 - ✅ Real authentication (JWT + bcrypt)
 - ✅ **Email verification (AWS SES with link + PIN code) - Phase 1.5**
 - ✅ **Password reset workflow - Phase 1.5**
@@ -32,6 +32,7 @@
 - ✅ **Public profiles (/{username}) - Phase 1.5**
 - ✅ **Event participation tracking - Phase 1.5**
 - ✅ **Event security (unique slugs, no ID enumeration) - Phase 1.5**
+- ✅ **QR code event check-in system - Phase 1.5** (requires physical presence at venue)
 - ✅ Real-time chat (Socket.IO for event & match rooms)
 - ✅ WebRTC P2P transfer UI mockup
 
@@ -113,13 +114,15 @@
 - `frontend/src/pages/ResetPasswordPage.jsx` - Reset password with token
 - `frontend/src/pages/ProfilePage.jsx` - **UPDATED: Edit profile (social media, location) - Phase 1.5**
 - `frontend/src/pages/PublicProfilePage.jsx` - **NEW: View other user profiles - Phase 1.5**
-- `frontend/src/pages/EventsPage.jsx` - **UPDATED: Real API, joined events first - Phase 1.5**
-- `frontend/src/pages/EventChatPage.jsx` - **UPDATED: Uses slugs instead of IDs - Phase 1.5**
+- `frontend/src/pages/EventsPage.jsx` - **UPDATED: Shows check-in requirement, dev-only QR access - Phase 1.5**
+- `frontend/src/pages/EventChatPage.jsx` - **UPDATED: Access control with check-in verification, Leave Event - Phase 1.5**
+- `frontend/src/pages/EventDetailsPage.jsx` - **NEW: QR code display, participant list - Phase 1.5**
+- `frontend/src/pages/EventCheckinPage.jsx` - **NEW: Check-in confirmation page - Phase 1.5**
 - `frontend/src/pages/MatchChatPage.jsx` - Private chat + WebRTC mockup
 - `frontend/src/components/common/PasswordStrengthIndicator.jsx` - Password strength indicator
 - `frontend/src/components/common/VerificationBanner.jsx` - Email verification banner
 - `frontend/src/contexts/AuthContext.jsx` - JWT authentication integration
-- `frontend/src/services/api.js` - **UPDATED: eventsAPI uses slugs - Phase 1.5**
+- `frontend/src/services/api.js` - **UPDATED: QR check-in methods (checkin, getDetails, leave) - Phase 1.5**
 - `frontend/src/services/socket.js` - Socket.IO client connection manager
 - `frontend/src/data/countries.js` - **NEW: List of 195 countries - Phase 1.5**
 
@@ -127,17 +130,18 @@
 - `backend/src/controllers/auth.js` - Register, login, email verification, password reset
 - `backend/src/controllers/user.js` - **UPDATED: Profile updates (social, location) - Phase 1.5**
 - `backend/src/controllers/wsdc.js` - WSDC API proxy for dancer lookup
-- `backend/src/routes/events.js` - **UPDATED: Uses slugs instead of IDs - Phase 1.5**
+- `backend/src/routes/events.js` - **UPDATED: QR check-in endpoints (checkin, details, leave), participant verification - Phase 1.5**
 - `backend/src/routes/users.js` - **UPDATED: Public profile endpoint - Phase 1.5**
-- `backend/src/socket/index.js` - **UPDATED: Slug-based event rooms, participation tracking - Phase 1.5**
+- `backend/src/socket/index.js` - **UPDATED: Participant verification before room join, security fix - Phase 1.5**
 - `backend/src/utils/email.js` - AWS SES email service with HTML templates
 - `backend/src/utils/auth.js` - Token generation utilities
 - `backend/src/middleware/auth.js` - Email verification middleware
 - `backend/src/middleware/validators.js` - **UPDATED: Social media URL validation - Phase 1.5**
 - `backend/src/server.js` - Express server with Socket.IO integration
-- `backend/prisma/schema.prisma` - **UPDATED: 7 tables (social, location, event_participants, slugs) - Phase 1.5**
+- `backend/prisma/schema.prisma` - **UPDATED: 8 tables (EventCheckinToken added) - Phase 1.5**
 - `backend/prisma/migrations/20251113151534_add_wsdc_and_email_verification/` - Phase 1.5 migration
 - `backend/prisma/migrations/20251113202500_add_event_slug/` - **NEW: Event slugs migration - Phase 1.5**
+- `backend/prisma/migrations/20251114125544_add_event_checkin_tokens/` - **NEW: QR check-in tokens - Phase 1.5**
 
 **Config:**
 - `docker-compose.yml` - nginx, frontend, backend, PostgreSQL
@@ -148,7 +152,7 @@
 
 ## Database Schema (Implemented - Prisma)
 
-7 tables with relations:
+8 tables with relations:
 - `users` - **EXTENDED in Phase 1.5:**
   - Base: id, username, email, password_hash, avatar, created_at, updated_at
   - **WSDC:** first_name, last_name, wsdc_id
@@ -158,6 +162,7 @@
   - **Location:** country, city
 - `events` - id, **slug (unique)**, name, location, start_date, end_date, description, worldsdc_id, participants_count
 - `event_participants` - **NEW in Phase 1.5:** id, user_id, event_id, joined_at (many-to-many)
+- `event_checkin_tokens` - **NEW in Phase 1.5:** id, event_id (unique), token (cuid, unique), created_at
 - `chat_rooms` - id, event_id, match_id, type (event/private), created_at
 - `messages` - id, room_id, user_id, content, type, created_at
 - `matches` - id, user1_id, user2_id, event_id, room_id, status, created_at
@@ -167,6 +172,7 @@
 - `20251112205214_init` - Initial schema
 - `20251113151534_add_wsdc_and_email_verification` - Phase 1.5 (email, WSDC, social, location)
 - `20251113202500_add_event_slug` - **Phase 1.5 (event security - unique slugs)**
+- `20251114125544_add_event_checkin_tokens` - **Phase 1.5 (QR code check-in system)**
 
 **Seed data:** 3 events, 2 users, event chat rooms
 
@@ -314,8 +320,10 @@ RUN apk add --no-cache openssl
 - `/reset-password/:token` - Reset password with token
 - `/profile` - Edit user profile (social media, location)
 - `/:username` - Public profile view
-- `/events` - Event list (joined events first)
-- `/events/:slug/chat` - Event chat (public, real-time Socket.IO)
+- `/events` - Event list (joined events first, check-in requirement notice)
+- `/events/:slug/chat` - Event chat (requires check-in, real-time Socket.IO)
+- `/events/:slug/details` - **NEW:** Event details with QR code, participant list
+- `/events/checkin/:token` - **NEW:** QR code check-in confirmation page
 - `/matches/:id/chat` - Private 1:1 chat + WebRTC mockup
 - `/matches/:id/rate` - Rate partner
 - `/history` - Match history
@@ -354,7 +362,7 @@ RUN apk add --no-cache openssl
 
 ---
 
-**Last Updated:** 2025-11-13
+**Last Updated:** 2025-11-14
 **Phase 1 Status:** ✅ COMPLETED - Backend Foundation (Express + PostgreSQL + JWT + Socket.IO)
 **Phase 1.5 Status:** ✅ COMPLETED - Email Verification & WSDC Integration & User Profiles & Security
   - AWS SES email verification (link + PIN)
@@ -364,4 +372,5 @@ RUN apk add --no-cache openssl
   - Public profiles (/{username})
   - Event participation tracking
   - Event security (unique slugs, no ID enumeration)
+  - **QR code event check-in system** (physical presence required, dev mode bypass)
 **Next Phase:** Phase 2 - Core Features (Matches API + Ratings + WebRTC)