perf: add rate limiting, validation, logging, and error handling

- Add express-rate-limit with tiered rate limits per endpoint
- Add express-validator for input validation on all API routes
- Add winston + morgan for structured logging
- Add node-cache for lottery result caching (5min TTL, 1000 max keys)
- Convert OCR to async task queue with max 2 concurrent jobs
- Add global error handler middleware
- Add React ErrorBoundary for client-side error handling
- Fix memory leaks in OCR task queue and lottery cache
- Add per-item error handling in batch ticket updates
- Fix SQL UPDATE to include user_id in WHERE clause

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -13,3 +13,9 @@ node_modules/
 # OS files
 .DS_Store
 Thumbs.db
+
+# Environment files
+.env
+
+# Application logs
+logs/