Add a Posters Page to the DDMAL Website

[kyuchia]

Description:

There is currently no centralized HTML page that visually presents all poster materials.

• The folder /posters/ exists in the repository root and contains poster files (PDF, JPG, PNG), but no index or HTML page for listing them.
• Posters are now categorized under /activities/ alongside Media, Presentations, and Publications:
  https://ddmal.music.mcgill.ca/activities/posters/
• However, this page currently lists files only as plain text.

Suggested tasks:

• Create an HTML page under /activities/posters/ that:
  • Displays poster thumbnails with links to complete files
  • Links posters to related projects or publications

[kyuchia]

Done
Add a poster gallery page with thumbnail and list views
#179

[fujinaga]

It took a bit of a time to load the thumbnail page. Can you make sure that all the thumbnail jpegs are compressed (but readable) to a uniform smallish size?

[kyuchia]

Thanks, Ich! I've compressed the thumbnails to a uniform smaller size. Please check the updated PR: #191. Let me know if any further changes are needed.