fix: improve node filtering by client base_version, set subscription content-type, and add hop_interval support for hysteria2

- Refactor node filtering logic to correctly handle client base_version requirements.
- Set appropriate Content-Type header for subscription responses.
- Add support for hop_interval configuration in hysteria2 node delivery.

app/Protocols/General.php

@@ -53,7 +53,7 @@ class General extends AbstractProtocol
                 $uri .= self::buildSocks($user['uuid'], $item);
             }
         }
-        return base64_encode($uri);
+        return response(base64_encode($uri))->header('content-type', 'text/plain');
     }
 
     public static function buildShadowsocks($password, $server)