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/Loon.php

@@ -41,7 +41,8 @@ class Loon extends AbstractProtocol
                 $uri .= self::buildHysteria($user['uuid'], $item, $user);
             }
         }
-        return response($uri, 200)
+        return response($uri)
+            ->header('content-type', 'text/plain')
             ->header('Subscription-Userinfo', "upload={$user['u']}; download={$user['d']}; total={$user['transfer_enable']}; expire={$user['expired_at']}");
     }