This PR refactors the configuration parser, replacing the old parser implementation with a new, more structured approach that includes validation and improved organization.
Key changes:
- Complete rewrite of the configuration parser using a map-based structure with built-in validation
- Addition of comprehensive validator functions for configuration values
- Renamed numerous configuration getter methods for better consistency
As youtubeVideoID is assigned to getVideoIDFromYouTubeURL(entry.URL),
there is no need to call the latter again when we can simly use youtubeVideoID
instead.
As mentioned in goquery's documentation (https://pkg.go.dev/github.com/PuerkitoBio/goquery#Single):
> By default, Selection.Find and other functions that accept a selector string
to select nodes will use all matches corresponding to that selector. By using
the Matcher returned by Single, at most the first match will be selected.
>
> The one using Single is optimized to be potentially much faster on large documents.
