Upgrade to Vue 3

[jpmckinney]

Vue 2.7 security support ended in 2023 https://endoflife.date/vue (commercial support available)

https://v2.vuejs.org/v2/guide/migration-vue-2-7.html
https://v3-migration.vuejs.org

• pelican-frontend (2.7)
  • Starting upgrade. Using Vuex 4 (currently on Vuex 3), but might switch to Pinia (endorsed by Vue as official state management library).
• spoonbill-web (2.6)
• data-registry doesn't use Vue, but has a few mentions because it uses bootstrap-vue styles.

Maybe worth trying Cursor to attempt the upgrade, if simply changing version numbers causes errors.