Replaces QR code implementation with lnbits-qrcode

Replaces the generic QR code generation with the lnbits-qrcode component.
This simplifies the code and utilizes a component specifically designed for LNbits applications.
Removes the input field for the invoice string as it is no longer necessary.

templates/castle/index.html

@@ -1181,31 +1181,10 @@
 
         <div class="text-center q-mb-md">
           <div class="text-subtitle2 q-mb-sm">Lightning Invoice Generated</div>
-          <qrcode-vue
+          <lnbits-qrcode
             :value="settleReceivableDialog.invoice"
-            :size="280"
-            level="M"
-            class="q-mb-md"
-          ></qrcode-vue>
-
-          <q-input
-            filled
-            dense
-            readonly
-            v-model="settleReceivableDialog.invoice"
-            label="Invoice"
-          >
-            <template v-slot:append>
-              <q-btn
-                flat
-                dense
-                icon="content_copy"
-                @click="copyToClipboard(settleReceivableDialog.invoice)"
-              >
-                <q-tooltip>Copy invoice</q-tooltip>
-              </q-btn>
-            </template>
-          </q-input>
+            :options="{width: 280}"
+          ></lnbits-qrcode>
 
           <div class="text-caption text-grey q-mt-sm">
             Waiting for payment...