chore(migration): merge Construct-X IAM changes into Tractus-X fork baseline

[devajipatil]

This PR migrates the existing Construct-X IAM service customizations from the legacy portal-iam_old repository into the newly created fork of the Tractus-X portal-iam repository.

The previous repository was not created as a GitHub fork, which limited the ability to synchronize with upstream changes. This PR merges the downstream branch feature/construct-x onto the upstream baseline while preserving Construct-X specific IAM configurations and behavior.

Scope:

• Merge legacy IAM changes into fork main
• Preserve downstream authentication and configuration adjustments
• Align repository history with Tractus-X upstream for future updates

Risk / Impact:

• Large diff expected due to unrelated history merge
• Requires validation of login flows, token issuance, and service integration after deployment

Validation Plan:

• Verify IAM service build and deployment in staging
• Test portal login, token exchange, and protected API access
• Confirm integration with backend and wallet services