Scope search designs for Upcoming and Past pages

[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

This PR scopes search for the Upcoming and Past conference pages and narrows the solution space before implementation. It reviews the current Jekyll structure, compares a few designs, and recommends the smallest viable approach pending approval.

• Problem

  • Finding a specific conference becomes harder on the larger Upcoming and especially Past listings.
  • The request is limited to improving discoverability on those two pages.

• What this PR covers

  • Repository and page-level discovery for index.html and past.html
  • Existing client-side scripting constraints in the current static Jekyll site
  • Practical search designs that fit the repo without changing CI, deployment, or data shape

• Options considered

  • Client-side DOM filter: add a search box on each page and filter rendered list items by name, location, dates, and status/video text
  • Lightweight indexed search: generate/search a small in-page or JSON-backed index with fuzzy matching
  • Site-wide search: broader/global search experience beyond the issue scope

• Recommended direction

  • Client-side DOM filter
  • Smallest change set
  • No new dependency
  • Fits the static architecture
  • Sufficient for the current/past page use case

• Fixes Add Search #41