feat(auth): implement OAuth2 exchange code flow for Microsoft login, update environment configurations, and enhance frontend SSO handling

.env.example

@@ -22,7 +22,15 @@ KEYCLOAK_FRONTEND_CLIENT_ID=anexo76-frontend
 DEBUG=True
 ENVIRONMENT=development
 
+CORE_DB_HOST=postgres-a76
+CORE_DB_PORT=5432
+CORE_DB_NAME=anexo76_core
+CORE_DB_USER=postgres
+CORE_DB_PASSWORD=postgres
+
+
 # ----- Frontend -----
 NODE_ENV=development
 PUBLIC_API_URL=http://localhost:8000
+PUBLIC_KEYCLOAK_REALM=master
 PUBLIC_KEYCLOAK_URL=http://localhost:8080