Add a grouped videos page for recent past conferences

[Copilot]

Pull Request Template: Add a Conference or Workshop

Thank you for contributing! Most PRs are to add a new conference or workshop. The following are to help ensure you've added everything correctly:

Conference/Workshop Details

• Name, Location, Date(s), Website URL and Status are required
• X / Twitter is Optional
• Location should be City + Country or Online
• Status can include information about registration, pricing, calls for proposals and can include links to all the above.

Checklist

• I have added the conference/workshop to the correct YAML file (_data/current.yml or _data/past.yml)
• The entry includes name, location, date(s), url and accurate status
• The entry is in chronological order (soonest to furtherest away)
• If there are any special characters in the name field (: or ; or '), the name must be in quotes (")
• I have checked for duplicates to avoid listing the same event twice
• Build runs successfully

Additional context

Adds a dedicated /videos/ page for past conferences with event recordings. The page pulls from _data/past.yml, shows only entries with video_url, limits the list to the 10 most recent entries, and groups them by year to support future expansion of the pattern.

• Page

  • Adds videos.html as a standalone Jekyll page rather than a post
  • Includes short introductory copy explaining the page purpose and how to extend it

• Data selection

  • Filters site.data.past to conferences with video_url
  • Uses existing past.yml ordering as the source of recency
  • Limits output to 10 entries

• Presentation

  • Splits the list by year (2024, 2023, 2021, etc.)
  • Shows the conference name, event date, and video link only

• Navigation

  • Adds Videos to the sub-navigation for discoverability

{% assign video_conferences = site.data.past | where_exp: "conference", "conference.video_url" %}

{% for conference in video_conferences limit: 10 %}
  {% assign conference_year = conference.dates | split: ", " | last %}
{% endfor %}