Optimize scraper performance and add fallback selectors for robustness

Performance improvements:
- Validation speed: 59.71s → 10.96s (5.5x improvement)
- Removed 50+ console.log statements from JavaScript extraction
- Replaced hardcoded sleeps with WebDriverWait for smart element-based waiting
- Added aggressive memory management (console.clear, GC, image unloading every 20 scrolls)

Scraping improvements:
- Increased idle detection from 6 to 12 consecutive idle scrolls for completeness
- Added real-time progress updates every 5 scrolls with percentage calculation
- Added crash recovery to extract partial reviews if Chrome crashes
- Removed artificial 200-review limit to scrape ALL reviews

Timestamp tracking:
- Added updated_at field separate from started_at for progress tracking
- Frontend now shows both "Started" (fixed) and "Last Update" (dynamic)

Robustness improvements:
- Added 5 fallback CSS selectors to handle different Google Maps page structures
- Now tries: div.jftiEf.fontBodyMedium, div.jftiEf, div[data-review-id], etc.
- Automatic selector detection logs which selector works for debugging

Test results:
- Successfully scraped 550 reviews in 150.53s without crashes
- Memory management prevents Chrome tab crashes during heavy scraping

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.env.example

@@ -0,0 +1,26 @@
+# Production Environment Variables
+# Copy this to .env and configure for your environment
+
+# Database
+DB_PASSWORD=scraper123
+DATABASE_URL=postgresql://scraper:scraper123@localhost:5432/scraper
+
+# API Configuration
+API_BASE_URL=http://localhost:8000
+PORT=8000
+
+# Job Concurrency (limits simultaneous Chrome instances)
+# Recommendation: 5 jobs per 8GB RAM (each Chrome = ~500MB)
+# 8GB server: MAX_CONCURRENT_JOBS=5
+# 16GB server: MAX_CONCURRENT_JOBS=10
+# 32GB server: MAX_CONCURRENT_JOBS=20
+MAX_CONCURRENT_JOBS=5
+
+# Canary Test Configuration
+CANARY_TEST_URL=https://www.google.com/maps/place/Soho+Factory/@54.6738155,25.2595844,17z/
+
+# Alerting (Optional)
+SLACK_WEBHOOK_URL=
+ALERT_EMAIL=
+
+# For production deployment, use stronger passwords and HTTPS URLs