feat: shop customer accounts (register/login + order history)

Schema:
- shop_customers (company_id, name, phone unique-per-tenant, email, password,
  client_id auto-linked, last_login_at)
- online_orders.shop_customer_id nullable FK

Auth:
- New 'shop' guard (session driver, shop_customers provider) in config/auth.php
- ShopCustomer Authenticatable with hashed password cast and BelongsToTenant
  global scope — login attempts naturally scoped to current tenant subdomain

Flow:
- ShopAuthController: register / login / logout / account
- Register auto-links to existing Client by phone match
- /shop/account: order history (only the logged customer's orders) + profile
- Checkout prefills name/phone/email from logged customer + sets
  shop_customer_id (and client_id from auto-link) on the placed order
- Layout nav switches between Login/Register and "👤 Name + Ieșire"

Tests (8 new):
- register creates customer + auto-login
- register auto-links existing Client by phone
- duplicate phone rejected
- login validates credentials
- /account requires auth (redirects to /shop/login)
- /account lists only the logged customer's orders
- checkout attaches shop_customer_id
- customers tenant-isolated

Full suite: 117 passed.

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

resources/views/shop/layout.blade.php

@@ -72,6 +72,15 @@
             <a href="/shop/cart">🛒 Coș
                 @if (($cartCount ?? 0) > 0)<span class="cart-badge">{{ $cartCount }}</span>@endif
             </a>
+            @auth('shop')
+                <a href="/shop/account">👤 {{ Auth::guard('shop')->user()->name }}</a>
+                <form method="POST" action="/shop/logout" style="display:inline;">@csrf
+                    <button type="submit" style="background:transparent;border:0;color:inherit;cursor:pointer;font:inherit;">Ieșire</button>
+                </form>
+            @else
+                <a href="/shop/login">Login</a>
+                <a href="/shop/register" style="background:rgba(255,255,255,.2);border-radius:6px;padding:4px 10px;">Înregistrare</a>
+            @endauth
         </nav>
     </div>
 </header>