- Fix daysAvailable to detect gaps >25 days (indicates unit was re-listed)
- Add /unit/:unitCode/price-history endpoint for full price history
- Add /analytics endpoint with monthly trends, seasonality analysis,
plan performance, historical comparisons, and price per sqft stats
- Add /last-scrape endpoint to return timestamp of most recent data
- Increase priceHistory limit from 5 to 30 for better chart data
