🛡️ Sentinel: Fix authorization bypass for cached inactive users

[Pmaster-dev]

🚨 Severity: HIGH
💡 Vulnerability: User records retrieved from Redis cache in @login_required bypassed is_active validation, allowing deactivated or inactive users with cached entries to access protected routes. Furthermore, unauthorized error responses leaked raw exception strings (str(e)).
🎯 Impact: Inactive accounts could bypass access controls. Raw exception details could leak internal database or cache error information to clients.
🔧 Fix: Validated is_active status on cached user data before authorizing requests and removed internal exception details from 401 error responses. Added comprehensive unit test coverage in tests/test_auth_utils.py.
✅ Verification: Ran pytest (7 passed) and pylint (score 7.92/10).

---

PR created automatically by Jules for task 17842397545404611078 started by @Pmaster-dev

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.