Update donate-neo swag selection for YEC 2025

This ticket is about updating donate-neo with new swag images and descriptions for the 2025 year-end campaign. This hasn't always gone smoothly the last few times we tried it - details below - and we want it to work a lot better this year. Here's the steps as I understand them:

• @lavamind and @mathieu work out the bugs in the JSON generation/import process and assure @mattlav it works. Review and revise instructions as needed.
• @nicob provides thumbnails for new products (new T-shirt, new pair of T-shirts, possibly a different sticker pack)
• @mattlav and @arturom deliver any needed item description copy
• @mattlav edits perk data in CiviCRM and exports JSON, per instructions
• @lavamind / TPA updates donate-neo with new perk data at launch time

Deployment : October 14, 15:00 UTC

• Master ticket about this process and its bugs
• Record of how this went in October, 2024
• Record of how this went in April, 2025

Adding this ticket for queue for Year End Campaign 2025 milestone. Please link to https://gitlab.torproject.org/tpo/operations/fundraising/-/issues/234

cc @mattlav