Refactor Netlify configuration and update dependencies for frontend

Commit notes

- Remove outdated netlify.toml file and replace it with a new configuration in frontend/netlify.toml for improved build and dev commands. - Update react-router and related dependencies to version 7.9.1 in frontend/package.json for enhanced routing capabilities. - Clean up react-router configuration by removing deprecated options.

This update streamlines the frontend setup and ensures compatibility with the latest React Router features.