fix(vue): use @submit to send forms, and catch users pressing return

lnbits/extensions/paywall/templates/paywall/index.html

@@ -81,7 +81,7 @@
 
     <q-dialog v-model="paywallDialog.show" position="top">
       <q-card class="q-pa-lg q-pt-xl" style="width: 500px">
-        <q-form class="q-gutter-md">
+        <q-form @submit="createPaywall" class="q-gutter-md">
           <q-select filled dense emit-value v-model="paywallDialog.data.wallet" :options="g.user.walletOptions" label="Wallet *">
           </q-select>
           <q-input filled dense
@@ -100,7 +100,7 @@
             <q-btn unelevated
               color="deep-purple"
               :disable="paywallDialog.data.amount == null || paywallDialog.data.amount < 0 || paywallDialog.data.url == null"
-              @click="createPaywall">Create paywall</q-btn>
+              type="submit">Create paywall</q-btn>
             <q-btn v-close-popup flat color="grey" class="q-ml-auto">Cancel</q-btn>
           </div>
         </q-form>