Update to newer LTS bases

[imnasnainaec]

• Use Docker Hardened Images
• GHAs, deployment, installer:
  • Python 3.12 -> 3.14
  • Ubuntu 24.04 -> 26.04
• .NET 8 -> 10
• Frontend:
  • React 18 -> 19
  • MUI 6 -> 7
  • ESLint 9 ->10
  • TypeScript 5 -> 6
• MongoDB 7 -> 8 (though the DHI is only for amd64)