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/checkout.blade.php

@@ -21,15 +21,15 @@
         @csrf
         <div class="field">
             <label>Nume complet *</label>
-            <input type="text" name="customer_name" value="{{ old('customer_name') }}" required>
+            <input type="text" name="customer_name" value="{{ old('customer_name', ($customer ?? null)?->name) }}" required>
         </div>
         <div class="field">
             <label>Telefon *</label>
-            <input type="text" name="customer_phone" value="{{ old('customer_phone') }}" required placeholder="+373…">
+            <input type="text" name="customer_phone" value="{{ old('customer_phone', ($customer ?? null)?->phone) }}" required placeholder="+373…">
         </div>
         <div class="field">
             <label>Email</label>
-            <input type="email" name="customer_email" value="{{ old('customer_email') }}">
+            <input type="email" name="customer_email" value="{{ old('customer_email', ($customer ?? null)?->email) }}">
         </div>
         <div class="field">
             <label>Livrare *</label>