Implement multi-domain licensing for v0.5.0

- Add multi-domain checkout support for WooCommerce Blocks
- Fix domain field rendering using ExperimentalOrderMeta slot
- Add DOM injection fallback for checkout field rendering
- Update translations with new multi-domain strings (de_CH)
- Update email templates for grouped license display
- Refactor account page to group licenses by product/order

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/License/LicenseManager.php

@@ -49,8 +49,11 @@ class LicenseManager
     ): ?License {
         global $wpdb;
 
-        // Check if license already exists for this order and product
-        $existing = $this->getLicenseByOrderAndProduct($orderId, $productId);
+        // Normalize domain first for duplicate detection
+        $normalizedDomain = $this->normalizeDomain($domain);
+
+        // Check if license already exists for this order, product, and domain
+        $existing = $this->getLicenseByOrderProductAndDomain($orderId, $productId, $normalizedDomain);
         if ($existing) {
             return $existing;
         }
@@ -161,6 +164,49 @@ class LicenseManager
         return $row ? License::fromArray($row) : null;
     }
 
+    /**
+     * Get all licenses for an order and product
+     *
+     * @return License[]
+     */
+    public function getLicensesByOrderAndProduct(int $orderId, int $productId): array
+    {
+        global $wpdb;
+
+        $tableName = Installer::getLicensesTable();
+        $rows = $wpdb->get_results(
+            $wpdb->prepare(
+                "SELECT * FROM {$tableName} WHERE order_id = %d AND product_id = %d ORDER BY created_at ASC",
+                $orderId,
+                $productId
+            ),
+            ARRAY_A
+        );
+
+        return array_map(fn(array $row) => License::fromArray($row), $rows ?: []);
+    }
+
+    /**
+     * Get license by order, product, and domain
+     */
+    public function getLicenseByOrderProductAndDomain(int $orderId, int $productId, string $domain): ?License
+    {
+        global $wpdb;
+
+        $tableName = Installer::getLicensesTable();
+        $row = $wpdb->get_row(
+            $wpdb->prepare(
+                "SELECT * FROM {$tableName} WHERE order_id = %d AND product_id = %d AND domain = %s",
+                $orderId,
+                $productId,
+                $domain
+            ),
+            ARRAY_A
+        );
+
+        return $row ? License::fromArray($row) : null;
+    }
+
     /**
      * Get all licenses for an order
      */