Changes: - Make JWT validator lazy-load JWKS on first use (not on init) - Thread-safe JWKS loading with mutex - Fixes test failures (JWKS 404 was panicking on NewValidator) - Add unit tests for JWT validation logic Tests now pass: ✅ Check permissions (sqs:read, sqs:write, wildcard) ✅ Reject empty/invalid/malformed tokens ✅ Handle missing permissions claim All 100% passing with no external dependencies.