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>

app/Filament/Tenant/Resources/PartResource/RelationManagers/CrossRefsRelationManager.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace App\Filament\Tenant\Resources\PartResource\RelationManagers;
+
+use Filament\Actions;
+use Filament\Forms;
+use Filament\Resources\RelationManagers\RelationManager;
+use Filament\Schemas\Schema;
+use Filament\Tables;
+use Filament\Tables\Table;
+
+class CrossRefsRelationManager extends RelationManager
+{
+    protected static string $relationship = 'crossRefs';
+
+    protected static ?string $title = 'Coduri cross (OEM/echivalente)';
+
+    public function form(Schema $schema): Schema
+    {
+        return $schema->components([
+            Forms\Components\TextInput::make('cross_article')->label('Cod echivalent')->required()->maxLength(64),
+            Forms\Components\TextInput::make('brand')->label('Brand')->maxLength(64),
+        ]);
+    }
+
+    public function table(Table $table): Table
+    {
+        return $table
+            ->recordTitleAttribute('cross_article')
+            ->columns([
+                Tables\Columns\TextColumn::make('cross_article')->label('Cod')->searchable(),
+                Tables\Columns\TextColumn::make('brand')->placeholder('—'),
+            ])
+            ->headerActions([Actions\CreateAction::make()])
+            ->actions([Actions\EditAction::make(), Actions\DeleteAction::make()])
+            ->emptyStateHeading('Niciun cod cross')
+            ->emptyStateDescription('Adaugă coduri echivalente OEM/aftermarket ca să fie găsite în căutarea din magazin.');
+    }
+}