fix: update primary auth token retrieval

[mels-h]

Use json.access_token as primary token retrieval path.

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

Issue Number: #110

What is the new behavior?

• Updates the OAuth token extraction logic to use json.access_token as the primary source.
• Ensures compatibility with standard OAuth2 token responses.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud