Add 'Publish to Shopify' for locally-created products

New header action on the product edit page creates the entire product
(title, description, all variants) in Shopify via API. The returned
shopify_product_id and per-variant shopify_variant_ids are stored
locally. After success the page reloads so status badges update.
Button is hidden once the product is already linked to Shopify.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/Services/ShopifyService.php

@@ -76,6 +76,54 @@ class ShopifyService
         return $variants;
     }
 
+    public function createProduct(\App\Models\Product $product, \Illuminate\Support\Collection $sizes): array
+    {
+        $variants = $sizes->map(fn (ProductSize $s) => array_filter([
+            'option1' => $s->packing->name . ' ' . $s->packing->size . 'g',
+            'price'   => number_format((float) $s->price, 2, '.', ''),
+            'sku'     => $s->sku ?: null,
+            'barcode' => $s->gtin ?: null,
+        ]))->values()->toArray();
+
+        $body = [
+            'product' => [
+                'title'     => $product->title,
+                'body_html' => $product->description
+                    ? '<p>' . nl2br(e($product->description)) . '</p>'
+                    : '',
+            ],
+        ];
+
+        if (! empty($variants)) {
+            $body['product']['variants'] = $variants;
+        }
+
+        $response = Http::withHeader('X-Shopify-Access-Token', $this->token)
+            ->post("{$this->baseUrl}/products.json", $body);
+
+        if ($response->failed()) {
+            throw new \RuntimeException(
+                'Shopify-Fehler ' . $response->status() . ': ' . $response->body()
+            );
+        }
+
+        $shopifyProduct  = $response->json('product');
+        $shopifyVariants = $shopifyProduct['variants'];
+
+        // Match returned variants back to local sizes by index (same order as sent)
+        $variantMap = [];
+        foreach ($sizes as $index => $size) {
+            if (isset($shopifyVariants[$index])) {
+                $variantMap[$size->packing_id] = (string) $shopifyVariants[$index]['id'];
+            }
+        }
+
+        return [
+            'shopify_product_id' => (string) $shopifyProduct['id'],
+            'variants'           => $variantMap,
+        ];
+    }
+
     public function createVariant(string $shopifyProductId, ProductSize $size): string
     {
         $packing  = $size->packing;