feat: protect learning pages and rebuild cockpit

src/main/java/com/example/demo/security/LearningJwtUtil.java

@@ -14,6 +14,8 @@ import java.util.Map;
 @Component
 public class LearningJwtUtil {
 
+    public static final String AUTH_COOKIE_NAME = "learning_demo_token";
+
     @Value("${learning.auth.jwt.secret}")
     private String secret;
 
@@ -52,6 +54,10 @@ public class LearningJwtUtil {
         return Map.copyOf(parse(token));
     }
 
+    public long expirationMillis() {
+        return expiration;
+    }
+
     private Claims parse(String token) {
         return Jwts.parser().verifyWith(key()).build().parseSignedClaims(token).getPayload();
     }