[feature] Price detection & tracking for listing pages

I want to monitor a certain GPU's price, so I searched for the model and ordered the results by price ascending. The specific brand is irrelevant, meaning the first result might change over time. I have a "regular" watch that can track price changes to that first item, but I wanted to leverage the price tracker so I'm only alerted of changes below a certain price.

The current price tracker only works for single page products, but maybe it could be extended to listing pages? Even if it required a manual selector, so it can be pointed to the first item instead of having to guess it.

For now I'm using a price detection watch with a browser action that automatically clicks and navigates to the page of the first result, but for that I need to use Playwright and I wanted to avoid that if possible.

Start by reading the current price tracker entry point and the browser action flow described in the issue. Compare how single-product pages are handled with the requested listing-page case, including manual selection of the first result. Done means a listing page can track the selected item's price without requiring Playwright.

Written by the indexing model from the issue text.