Implement Secure JWT Error Handling

[viceda-s]

Problem: Token validation exceptions are swallowed silently, making it impossible to audit malicious token attempts or debug authentication issues.

Acceptance Criteria:

• Add explicit log.warn for JwtException inside JwtAuthFilter.
• Ensure the filter chain continues securely (returning 401 via HttpStatusEntryPoint) without exposing stack traces to the client.

[viceda-s]

Added log.warn in JwtAuthFilter to capture token errors while allowing the filter chain to return 401 Unauthorized cleanly via HttpStatusEntryPoint.