feat(11-receipt-print): phase 11 complete — receipt preview, print & PDF

Add receipt show/print/pdf endpoints with dompdf integration.
Active preview and PDF links in order Documents tab.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

resources/scss/shared/_ui-components.scss

@@ -244,3 +244,41 @@
   color: var(--c-primary);
   background: #edf2ff;
 }
+
+.receipt-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: flex-start;
+  margin-bottom: 16px;
+  padding-bottom: 12px;
+  border-bottom: 2px solid var(--c-text-strong);
+
+  &__seller {
+    flex: 1;
+
+    strong {
+      font-size: 14px;
+      display: block;
+      margin-bottom: 4px;
+    }
+  }
+
+  &__title {
+    text-align: right;
+
+    h1 {
+      font-size: 18px;
+      font-weight: 700;
+      margin-bottom: 4px;
+    }
+  }
+}
+
+.receipt-print {
+  max-width: 700px;
+  margin: 0 auto;
+
+  @media print {
+    max-width: 100%;
+  }
+}