Fix security warnings and update dependency versions

[gary-archer]

• Use Node.js 22 as the minimum version
• Update dependencies to fix security warnings
• Upgrade to the latest Keycloak 26 and fix a deployment error if you import the admin user and also set an environment variable
• Minor webpack changes to copy HTML / CSS to the dist folder after every edit to make SPA deployment and development cleaner
• Add bootstrap CSS to the repo rather than complicate the CSP
• Tested the end-to-end deployment