feat: add fallback to most recent prices when requested date has no data

- When no prices exist for the requested date, query for the most
  recent available date and return those prices instead
- Log informational message when falling back to alternate date

app/main.py

@@ -144,6 +144,17 @@ async def get_stored_prices(
             CompanyPrice.scrape_date == date
         ).all()
         
+        # Fallback: if no prices for requested date, get most recent ones
+        if not prices:
+            latest_date_result = db.query(CompanyPrice.scrape_date).order_by(
+                CompanyPrice.scrape_date.desc()
+            ).first()
+            if latest_date_result:
+                prices = db.query(CompanyPrice).filter(
+                    CompanyPrice.scrape_date == latest_date_result[0]
+                ).all()
+                logger.info(f"No prices for {date}, returning {len(prices)} prices from {latest_date_result[0]}")
+        
         return [
             PriceRecord(
                 company_name=p.company_name,