Drop react-scripts

The framework has been [deprecated], and it's blocking several dependabot upgrades. We should remove the dependency by ejecting or switching to another framework.

[deprecated]: https://github.com/facebook/create-react-app/blob/main/README.md

Start by locating the frontend dependency configuration and entry points that use react-scripts. Compare the issue's two stated paths—ejecting or switching frameworks—and determine which is compatible with the project. Done means react-scripts is removed and the blocked Dependabot upgrades can proceed without breaking the frontend.

Written by the indexing model from the issue text.