check validity on app import form

dashboard/src/components/AppImportDialog.vue

@@ -24,6 +24,11 @@ const encryptionPasswordHint = ref('');
 const encryptionPassword = ref('');
 const encryptedFilenames = ref(false);
 
+const isFormValid = ref(false);
+async function validateForm() {
+  isFormValid.value = form.value && form.value.checkValidity();
+}
+
 async function onSubmit() {
   if (!form.value.reportValidity()) return;
 
@@ -261,7 +266,7 @@ defineExpose({
 
     <Dialog ref="dialog" :title="$t('app.importBackupDialog.title')"
      :confirm-label="$t('app.importBackupDialog.importAction')"
-     :confirm-active="!busy"
+     :confirm-active="!busy && isFormValid"
      :confirm-busy="busy"
      :reject-label="$t('main.dialog.cancel')"
      :reject-active="!busy"
@@ -281,7 +286,7 @@ defineExpose({
           </button>
         </p>
 
-        <form @submit.prevent="onSubmit()" autocomplete="off" ref="form">
+        <form @submit.prevent="onSubmit()" autocomplete="off" ref="form" @input="validateForm()">
           <fieldset :disabled="busy">
             <input style="display: none;" type="submit"/>