Add Kr currency unit and period display

- Show Kr after all amounts and prices
- Replace batch reference with period (first-last date)
- Same period shown on all customer invoices

templates/customer.html

@@ -104,7 +104,7 @@
     <div class="header">
         <div>
             <h1>Faktura - Kund {{ customer.customer_number }}</h1>
-            <div>Batchar: {{ batches | join(", ") }}</div>
+            <div>Period: {{ period }}</div>
         </div>
         <div class="meta">
             <div>Genererad: {{ generated_date }}</div>
@@ -118,7 +118,7 @@
             <span>{{ card.transactions.len() }} transaktioner</span>
         </div>
         <div class="card-summary">
-            Summa: {{ card.total_amount }} | Volym: {{ card.total_volume }} L
+            Summa: {{ card.total_amount }} Kr | Volym: {{ card.total_volume }} L
         </div>
         <table>
             <thead>
@@ -154,7 +154,7 @@
     {% endfor %}
 
     <div class="grand-total">
-        Totalsumma:<span>{{ customer.grand_total }}</span>
+        Totalsumma:<span>{{ customer.grand_total }} Kr</span>
     </div>
 </body>
 </html>