🛡️ Sentinel: [MEDIUM] Fix sensitive information disclosure in auth utils

[Pmaster-dev]

🚨 Severity: MEDIUM
💡 Vulnerability: Information disclosure via exception details in authentication decorator
🎯 Impact: Unauthenticated attackers could trigger exceptions to reveal internal application implementation details and stack trace snippets
🔧 Fix: Removed str(e) exception details from the login_required JSON error response in auth/utils.py
✅ Verification: Added unit test in tests/test_auth.py and ran pytest suite successfully

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PR created automatically by Jules for task 4880810069611738575 started by @Pmaster-dev

[google-labs-jules]

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