feat: code restructuring to enable local build

[plakkara-bc]

Description

Summary
Added support for running the application locally without requiring SSO/Keycloak authentication. This makes it easier for developers to test and debug the application without setting up a full SSO environment.

How it works
Frontend:

When VITE_APP_ENV=LOCAL, the app bypasses Keycloak and uses a mock user/token
No SSO server connection required
Backend:

When NODE_ENV=local, JWT signature verification is skipped
Tokens are still decoded to extract user info, but signatures aren't validated against Keycloak

Environment Variables to Enable Local Mode
Backend (.env):

NODE_ENV=local
USE_MOCK_DATA=true

Frontend (.env):
VITE_APP_ENV=LOCAL

Quick Start

• Copy [.env.example] to [.env] in both frontend and backend
• Set the values above
• Run npm run start:dev in backend
• Run npm run dev in frontend

⚠️ Warning
These settings should only be used for local development. Never deploy with NODE_ENV=local or VITE_APP_ENV=LOCAL in any shared environment.

[mdiapenabc]

Let's merge the other PR first