views: add checkout pages

views/checkout/cancel.php

@@ -0,0 +1,12 @@
+<section class="block">
+    <div class="wrap" style="max-width:560px;text-align:center">
+        <div class="empty">
+            <h1>Checkout cancelled</h1>
+            <p class="muted">No payment was taken. Your cart is still saved if you want to try again.</p>
+            <div class="row gap-lg" style="justify-content:center">
+                <a class="btn btn--primary mt" href="/checkout">Return to checkout</a>
+                <a class="btn mt" href="/cart">View cart</a>
+            </div>
+        </div>
+    </div>
+</section>