feat: Increase Amazon limit to 50 and fix screenshot framing

- Increased default Amazon search results limit from 20 to 50 in backend and frontend
- Improved TrackingScraperService to target main product area on Amazon (avoiding reviews)
- Added specific selectors for Amazon product page (#imgTagWrapperId, #productTitle, etc.)

app/services/amazon_scraper_service.py

@@ -277,7 +277,7 @@ class AmazonScraperService:
             pass
 
     @classmethod
-    async def scrape_search(cls, query: str, max_results: int = 20) -> list[AmazonProduct]:
+    async def scrape_search(cls, query: str, max_results: int = 50) -> list[AmazonProduct]:
         """
         Scrape Amazon France search results