🐛 fix(comments): fix malformed URLs in Isso mails

[welpo]

Description

This PR aims to address the issue of malformed URLs in the email notifications generated by Isso, as detailed in #210.

Changes

• Modified the Tera template to change how data-isso-id and data-title are set.

Implementation details

The previous setup used the page's slug to populate data-isso-id and data-title. This resulted in URLs lacking a separating slash between the domain and the identifier/post in the email notifications.

The new setup uses default_lang_url in Tera templates to populate these attributes:

{%- set default_lang_url = current_path | replace(from='/' ~ lang ~ '/', to = '/') -%}
    data-isso-id="{{ default_lang_url }}"
    data-title="{{ default_lang_url }}"
{% endif %}

Limitations

While this solution is effective for most use-cases, it's not perfect. Specifically, if a post does not exist in a non-default language, the URL in the email notification will still return 404. However, as far as I know, this is the only way to merge comments in multilingual sites effectively.

Testing

1. Enable Isso comments on the site.
2. Enable email notifications in the Isso setup.
3. Configure page_id_is_slug = true in [extra.isso].
4. Submit a comment.
5. Verify that the received email notification contains the correct and functional link to the comment.