Bump next in /webapp in the npm_and_yarn group across 1 directory

Bumps the npm_and_yarn group with 1 update in the /webapp directory: [next](https://github.com/vercel/next.js).


Updates `next` from 15.2.4 to 15.4.7
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.2.4...v15.4.7)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.4.7
  dependency-type: direct:production
  dependency-group: npm_and_yarn
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]