feat: improve f-droid link handling

- Handle only app-specific links
- Add pathPrefix to handle only app-specific links

The pathPattern .*/packages/.*\..* ensures that the path contains /packages/ followed by a string with at least one dot, which is characteristic of a package name. This will correctly handle URLs like
  https://f-droid.org/en/packages/com.klee.sapio/ and ignore URLs like https://f-droid.org/en/packages/.