Add licensed variable product support for duration-based licenses (v0.5.3)

Customers can now purchase licenses with different durations (monthly,
yearly, lifetime) through WooCommerce product variations. Each variation
can have its own license validity settings.

New features:
- LicensedVariableProduct class for variable licensed products
- LicensedProductVariation class for individual variations
- Per-variation license duration and max activations settings
- Duration labels in checkout (Monthly, Quarterly, Yearly, etc.)
- Full support for WooCommerce Blocks checkout with variations
- Updated translations for German (de_CH)

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

src/Checkout/StoreApiExtension.php

@@ -100,6 +100,9 @@ final class StoreApiExtension
                             'product_id' => [
                                 'type' => 'integer',
                             ],
+                            'variation_id' => [
+                                'type' => 'integer',
+                            ],
                             'domains' => [
                                 'type' => 'array',
                                 'items' => [
@@ -162,6 +165,7 @@ final class StoreApiExtension
             }
 
             $productId = (int) $item['product_id'];
+            $variationId = isset($item['variation_id']) ? (int) $item['variation_id'] : 0;
             $domains = [];
 
             foreach ($item['domains'] as $domain) {
@@ -172,10 +176,17 @@ final class StoreApiExtension
             }
 
             if (!empty($domains)) {
-                $normalized[] = [
+                $entry = [
                     'product_id' => $productId,
                     'domains' => $domains,
                 ];
+
+                // Include variation_id if present
+                if ($variationId > 0) {
+                    $entry['variation_id'] = $variationId;
+                }
+
+                $normalized[] = $entry;
             }
         }
 
@@ -267,10 +278,23 @@ final class StoreApiExtension
         // Check for licensed_domains in classic format (from DOM injection)
         if (empty($domainData) && isset($requestData['licensed_domains']) && is_array($requestData['licensed_domains'])) {
             $domainData = [];
-            foreach ($requestData['licensed_domains'] as $productId => $domains) {
+            $variationIds = $requestData['licensed_variation_ids'] ?? [];
+
+            foreach ($requestData['licensed_domains'] as $key => $domains) {
                 if (!is_array($domains)) {
                     continue;
                 }
+
+                // Parse key - could be "productId" or "productId_variationId"
+                $parts = explode('_', (string) $key);
+                $productId = (int) $parts[0];
+                $variationId = isset($parts[1]) ? (int) $parts[1] : 0;
+
+                // Also check for hidden variation ID field
+                if ($variationId === 0 && isset($variationIds[$key])) {
+                    $variationId = (int) $variationIds[$key];
+                }
+
                 $normalizedDomains = [];
                 foreach ($domains as $domain) {
                     $sanitized = sanitize_text_field($domain);
@@ -279,10 +303,16 @@ final class StoreApiExtension
                     }
                 }
                 if (!empty($normalizedDomains)) {
-                    $domainData[] = [
-                        'product_id' => (int) $productId,
+                    $entry = [
+                        'product_id' => $productId,
                         'domains' => $normalizedDomains,
                     ];
+
+                    if ($variationId > 0) {
+                        $entry['variation_id'] = $variationId;
+                    }
+
+                    $domainData[] = $entry;
                 }
             }
         }