Store server type on save

js/trserver.js

@@ -273,8 +273,9 @@ class trserver extends EventTarget {
 
     getInstanceData() {
         return {
-            'rpcurl': this.#rpcurl,
-            'auth': this.#authHeader
+            type: 'transmission',
+            rpcurl: this.#rpcurl,
+            auth: this.#authHeader
         };
     }