docs: update documentation after Phase 1 completion

Updated documentation to reflect completion of Phase 1 (Backend Foundation):

- SESSION_CONTEXT.md: Updated status to Phase 1 completed, ~50% progress
  - Added completed backend infrastructure details
  - Updated tech stack with actual versions
  - Added Phase 2 next steps (Matches API, Ratings, WebRTC)
  - Updated key files list with backend files
  - Added Prisma OpenSSL bug fix to known issues

- TODO.md: Marked Phase 1 as completed, Phase 2 as active
  - Moved Phase 1 steps to completed section with checkmarks
  - Added detailed Phase 2 tasks (4 steps: Matches API, Ratings API, WebRTC Signaling, WebRTC File Transfer)
  - Reorganized future phases (removed Phase 2 from future, renumbered)

- COMPLETED.md: Added comprehensive Phase 1 completion record
  - All 4 steps documented with checkmarks
  - Test coverage statistics (81.19% overall)
  - Infrastructure updates
  - Bug fixes (OpenSSL for Prisma)
  - Git commit history for Phase 1

docs/COMPLETED.md

@@ -11,6 +11,94 @@
 
 ---
 
+## ✅ Phase 1: Backend Foundation (COMPLETED)
+
+**Completed:** 2025-11-12
+**Time Spent:** ~14 hours
+**Status:** Production-ready backend with 81%+ test coverage
+
+### Step 1: Backend Setup
+- [x] Docker backend container (Node.js 20 Alpine)
+- [x] Express 4.18.2 server setup
+- [x] Folder structure (controllers, routes, middleware, utils, __tests__)
+- [x] Health check endpoint `GET /api/health`
+- [x] nginx proxy for `/api/*`
+- [x] GET `/api/events` endpoint with Prisma
+- [x] Unit tests: 7 tests passing
+- [x] CORS configuration
+
+### Step 2: PostgreSQL Setup
+- [x] PostgreSQL 15 Alpine container
+- [x] Prisma ORM 5.8.0 integration
+- [x] Database schema with 6 tables:
+  - users (id, username, email, password_hash, avatar, created_at)
+  - events (id, name, location, start_date, end_date, description, worldsdc_id)
+  - chat_rooms (id, event_id, match_id, type, 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)
+  - ratings (id, match_id, rater_id, rated_id, score, comment, created_at)
+- [x] Relations and indexes
+- [x] Migrations (prisma migrate)
+- [x] Seed data (3 events, 2 users, chat rooms)
+- [x] Volume persistence for database
+- [x] **Bug fix:** OpenSSL compatibility for Prisma (added `apk add openssl` to Dockerfile)
+
+### Step 3: Authentication API
+- [x] Dependencies: bcryptjs 2.4.3, jsonwebtoken 9.0.2, express-validator 7.3.0
+- [x] Password hashing with bcrypt (10 salt rounds)
+- [x] JWT token generation (24h expiry)
+- [x] Endpoints:
+  - `POST /api/auth/register` - Create account
+  - `POST /api/auth/login` - Login with JWT
+  - `GET /api/users/me` - Get current user (protected)
+- [x] Auth middleware for protected routes
+- [x] Input validation and sanitization
+- [x] Frontend integration (AuthContext + API service layer)
+- [x] Unit tests: 30 tests passing, 78.26% coverage
+
+### Step 4: WebSocket Chat (Socket.IO)
+- [x] Socket.IO 4.8.1 server installation
+- [x] HTTP server integration with Express
+- [x] JWT authentication for socket connections
+- [x] Event rooms implementation:
+  - `join_event_room` - Join event chat
+  - `leave_event_room` - Leave event chat
+  - `send_event_message` - Send message to event room
+  - `event_message` - Receive messages
+  - `active_users` - Active users list
+  - `user_joined` / `user_left` - Notifications
+- [x] Match rooms implementation:
+  - `join_match_room` - Join private 1:1 chat
+  - `send_match_message` - Send private message
+  - `match_message` - Receive private messages
+- [x] Message persistence to PostgreSQL
+- [x] Active users tracking with Map data structure
+- [x] Automatic cleanup on disconnect
+- [x] nginx WebSocket proxy for `/socket.io` (7d timeout)
+- [x] Frontend integration:
+  - socket.io-client installation
+  - Socket service layer (connectSocket, getSocket, disconnectSocket)
+  - EventChatPage with real-time messaging
+  - MatchChatPage with real-time private chat
+  - Connection status indicators
+- [x] Unit tests: 12 tests passing, 89.13% coverage for Socket.IO module
+- [x] Overall test coverage: 81.19%
+
+### Infrastructure Updates
+- [x] docker-compose.yml with 4 services (nginx, frontend, backend, db)
+- [x] nginx config for API proxy and WebSocket support
+- [x] Backend Dockerfile with OpenSSL for Prisma
+- [x] Environment variables (.env) for database and JWT
+
+### Git Commits (Phase 1)
+1. `docs: optimize documentation structure for token efficiency`
+2. `feat: add backend setup with Express and unit tests`
+3. `feat: add PostgreSQL database with Prisma ORM`
+4. `feat: add JWT authentication with complete test coverage`
+5. `feat: implement real-time chat with Socket.IO`
+
+---
+
 ## 🐳 1. Setup projektu i infrastruktura
 
 ### Docker Compose