security: implement CRITICAL and MEDIUM security fixes with environment profiles

This commit addresses all CRITICAL and MEDIUM security vulnerabilities
identified in the security audit with environment-aware configuration.

## Docker Compose Profiles

- Added docker-compose.dev.yml for development (relaxed security)
- Added docker-compose.prod.yml for production (strict security)
- Environment-specific configurations for rate limiting, CSRF, logging

## CRITICAL Fixes (P0)

1. Fixed insecure random number generation
   - Replaced Math.random() with crypto.randomBytes() for verification codes
   - Now cryptographically secure

2. Implemented rate limiting
   - express-rate-limit for all endpoints
   - Strict limits on auth endpoints (5 attempts in dev=off, prod=5)
   - Email endpoint limits (20 in dev, 3 in prod)
   - API-wide rate limiting

3. Added request body size limits
   - Development: 50MB (for testing)
   - Production: 10KB (security)

4. Fixed user enumeration vulnerability
   - Generic error message for registration
   - No disclosure of which field exists

5. Added security headers
   - helmet.js with CSP, HSTS, XSS protection
   - No-sniff, hide powered-by headers

## MEDIUM Fixes (P1)

6. Strengthened password policy
   - Environment-aware validation (8+ chars)
   - Production: requires uppercase, lowercase, number
   - Development: relaxed for testing

7. Enhanced input validation
   - Validation for all auth endpoints
   - WSDC ID validation (numeric, max 10 digits)
   - Name validation (safe characters only)
   - Email normalization

8. Added input sanitization
   - DOMPurify for XSS prevention
   - Sanitize all user inputs in emails
   - Timing-safe string comparison for tokens

9. Improved error handling
   - Generic errors in production
   - Detailed errors only in development
   - Proper error logging

10. Enhanced CORS configuration
    - Whitelist-based origin validation
    - Environment-specific allowed origins
    - Credentials support

## New Files

- backend/src/config/security.js - Environment-aware security config
- backend/src/middleware/rateLimiter.js - Rate limiting middleware
- backend/src/utils/sanitize.js - Input sanitization utilities
- backend/.env.example - Development environment template
- backend/.env.production.example - Production environment template
- docker-compose.dev.yml - Development overrides
- docker-compose.prod.yml - Production configuration
- docs/DEPLOYMENT.md - Complete deployment guide
- docs/SECURITY_AUDIT.md - Full security audit report
- .gitignore - Updated to exclude .env files

## Dependencies Added

- helmet (^8.1.0) - Security headers
- express-rate-limit (^8.2.1) - Rate limiting
- dompurify (^3.3.0) - XSS prevention
- jsdom (^27.2.0) - DOM manipulation for sanitization

## Testing

- ✅ Password validation works (weak passwords rejected)
- ✅ User enumeration fixed (generic error messages)
- ✅ WSDC lookup functional
- ✅ Registration flow working
- ✅ Rate limiting active (environment-aware)
- ✅ Security headers present

## Usage

Development:
  docker compose -f docker-compose.yml -f docker-compose.dev.yml up

Production:
  docker compose -f docker-compose.yml -f docker-compose.prod.yml up

See docs/DEPLOYMENT.md for detailed instructions.

.gitignore

@@ -1,25 +1,23 @@
 # Dependencies
 node_modules/
-frontend/node_modules/
-backend/node_modules/
+*/node_modules/
 
-# Environment variables
+# Environment files - NEVER commit secrets!
 .env
 .env.local
+.env.production
 .env.*.local
+backend/.env
+frontend/.env
 
-# Logs
-logs/
-*.log
-npm-debug.log*
-yarn-debug.log*
-yarn-error.log*
-
-# Build output
+# Build outputs
 dist/
 build/
-frontend/dist/
-backend/dist/
+*.log
+
+# OS files
+.DS_Store
+Thumbs.db
 
 # IDE
 .vscode/
@@ -28,11 +26,33 @@ backend/dist/
 *.swo
 *~
 
-# OS
-.DS_Store
-Thumbs.db
+# Docker volumes
+postgres_data/
 
-# Docker
-*.pid
-*.seed
-*.pid.lock
+# Logs
+logs/
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Testing
+coverage/
+.nyc_output/
+
+# Prisma
+backend/prisma/migrations/*_draft/
+
+# Temporary files
+tmp/
+temp/
+*.tmp
+
+# SSL certificates (if self-signed for development)
+ssl/*.pem
+ssl/*.key
+ssl/*.crt
+
+# Backups
+backups/*.sql
+backups/*.dump