feat: add baseurl to admin ui settings (#2644)

* feat: add baseurl to admin ui settings

server tab with a hint that it is currently not used.

i ran into an issue developing an extension where i needed to know the
url inside a task, where i cannot pass the `Request` object.
so i depend on `settings.lnbits_baseurl` there

lnbits/core/templates/admin/_tab_server.html

@@ -1,24 +1,19 @@
 <q-tab-panel name="server">
   <q-card-section class="q-pa-none">
     <h6 class="q-my-none">Server Management</h6>
-    <br />
     <div>
       <div class="row">
-        <div class="col">
-          <p>Server Info</p>
-          <ul>
-            <li
-              v-if="settings.lnbits_data_folder"
-              v-text="'SQlite: ' + settings.lnbits_data_folder"
-            ></li>
-            <li
-              v-if="settings.lnbits_database_url"
-              v-text="'Postgres: ' + settings.lnbits_database_url"
-            ></li>
-          </ul>
+        <div class="col-md-6">
+          <p>Base URL</p>
+          <q-input
+            filled
+            v-model.number="formData.lnbits_baseurl"
+            label="Static/Base url for the server"
+          ></q-input>
           <br />
         </div>
       </div>
+      <h6 class="q-my-none">Currency Settings</h6>
       <div class="row q-col-gutter-md">
         <div class="col-12 col-md-6">
           <p>Allowed currencies</p>