fix(backend): Restore service flow and admin management integration

backend/video-common/src/main/java/com/nuaa/video/common/utils/JwtUtils.java

@@ -20,7 +20,7 @@ import java.util.function.Function;
 @Component
 public class JwtUtils {
 
-    @Value("${jwt.secret:video-platform-secret-key-2024-nuaa}")
+    @Value("${jwt.secret}")
     private String secret;
 
     @Value("${jwt.expiration:86400}")
@@ -120,4 +120,4 @@ public class JwtUtils {
         byte[] keyBytes = secret.getBytes();
         return Keys.hmacShaKeyFor(keyBytes);
     }
-}
+}