invoice: add a PAID stamp

If the invoice has a Paid toggle, this will show a little "PAID" stamp
on the invoice once that's checked.

invoices/exampleData.js

@@ -42,4 +42,5 @@ const exampleData = {
   Deduction: null,
   Taxes: null,
   Total: 615,
+  Paid: true,
 };

invoices/index.html

@@ -178,6 +178,11 @@
             </div>
           </div>
         </template>
+        <template v-if="invoice.Paid">
+          <div class="paid">
+            PAID
+          </div>
+        </template>
 
         <div class="footer">
           <div class="thanks">

invoices/invoice.css

@@ -167,6 +167,18 @@ div.instructions, .newlined, p.note {
   white-space: pre-line;
 }
 
+div.paid {
+  position: relative;
+  left: 40%;
+  color: red;
+  rotate: 15deg;
+  font-size: 80px;
+  top: 20px;
+  border: 5px solid red;
+  float: left;
+  font-weight: bolder;
+}
+
 .app {
   position: relative;
 }

invoices/invoice.js

@@ -151,7 +151,8 @@ function updateInvoice(row) {
     // Add some guidance about columns.
     const want = new Set(Object.keys(addDemo({})));
     const accepted = new Set(['References']);
-    const importance = ['Number', 'Client', 'Items', 'Total', 'Invoicer', 'Due', 'Issued', 'Subtotal', 'Deduction', 'Taxes', 'Note'];
+    const importance = ['Number', 'Client', 'Items', 'Total', 'Invoicer', 'Due', 
+                        'Issued', 'Subtotal', 'Deduction', 'Taxes', 'Note', 'Paid'];
     if (!(row.Due || row.Issued)) {
       const seen = new Set(Object.keys(row).filter(k => k !== 'id' && k !== '_error_'));
       const help = row.Help = {};