Stage 12 — Online Store: public catalog + cart + orders

Schema:
- online_orders (token-tracked, status workflow, delivery method/fee)
- online_order_items (price snapshot, fulfilled flag)
- part_cross_refs (OEM/equivalent codes for search)
- parts.is_published (shop visibility)

Storefront (ShopController, tenant subdomain, /shop):
- Catalog with search across name/article/brand/cross-refs, category +
  in-stock filters, live stock, white-label themed layout
- Part detail page with cross-ref codes
- VIN search → VinDecoder → guided catalog search
- Session cart (per-tenant key), guest checkout, order confirmation page
- Respects settings.shop.enabled (404 when off); tenant-guarded

Part::searchPublished matches cross-ref articles via whereHas.

Order notifications (ShopOrderNotifier, best-effort):
- Staff: Web Push to active users
- Customer: Telegram if phone matches a linked client

Filament (tenant):
- OnlineOrderResource under "Magazin" nav group, status workflow,
  items relation, "Onorează" action issues stock via WarehouseService (FIFO)
- PartResource: is_published toggle + column + bulk publish/unpublish +
  CrossRefsRelationManager
- Settings: shop section (enable, delivery methods, fee, free-over)
- Landing page: shop button when enabled

Tests (6 new):
- catalog 404 when disabled; lists published only; cross-ref search;
  order placement (token + items + total); fulfill issues stock;
  cross-tenant token isolation

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

resources/views/site/landing.blade.php

@@ -58,6 +58,11 @@
     @endif
     <h1>{{ $name }}</h1>
     <p>Autoservice profesional{{ $city ? ' — ' . $city : '' }}. Diagnostic, reparații, piese, ITP.</p>
+    @if (! empty($shopEnabled))
+        <a href="/shop" style="display:inline-block;margin-top:20px;background:#fff;color:{{ $themeColor }};padding:12px 28px;border-radius:8px;font-weight:700;text-decoration:none;">
+            🛒 Magazin piese online
+        </a>
+    @endif
 </header>
 
 @if (! empty($services))