feat: multi-module improvements across merchant, store, i18n, and customer systems

- Fix platform-grouped merchant sidebar menu with core items at root level
- Add merchant store management (detail page, create store, team page)
- Fix store settings 500 error by removing dead stripe/API tab
- Move onboarding translations to module-owned locale files
- Fix onboarding banner i18n with server-side rendering + context inheritance
- Refactor login language selectors to use languageSelector() function (LANG-002)
- Move HTTPException handling to global exception handler in merchant routes (API-003)
- Add language selector to all login pages and portal headers
- Fix customer module: drop order stats from customer model, add to orders module
- Fix admin menu config visibility for super admin platform context
- Fix storefront auth and layout issues
- Add missing i18n translations for onboarding steps (en/fr/de/lb)

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

app/modules/customers/services/admin_customer_service.py

@@ -8,7 +8,6 @@ Handles customer operations for admin users across all stores.
 import logging
 from typing import Any
 
-from sqlalchemy import func
 from sqlalchemy.orm import Session
 
 from app.modules.customers.exceptions import CustomerNotFoundException
@@ -98,9 +97,6 @@ class AdminCustomerService:
                 "customer_number": customer.customer_number,
                 "marketing_consent": customer.marketing_consent,
                 "preferred_language": customer.preferred_language,
-                "last_order_date": customer.last_order_date,
-                "total_orders": customer.total_orders,
-                "total_spent": float(customer.total_spent) if customer.total_spent else 0,
                 "is_active": customer.is_active,
                 "created_at": customer.created_at,
                 "updated_at": customer.updated_at,
@@ -134,25 +130,11 @@ class AdminCustomerService:
         total = query.count()
         active = query.filter(Customer.is_active == True).count()  # noqa: E712
         inactive = query.filter(Customer.is_active == False).count()  # noqa: E712
-        with_orders = query.filter(Customer.total_orders > 0).count()
-
-        # Total spent across all customers
-        total_spent_result = query.with_entities(func.sum(Customer.total_spent)).scalar()
-        total_spent = float(total_spent_result) if total_spent_result else 0
-
-        # Average order value
-        total_orders_result = query.with_entities(func.sum(Customer.total_orders)).scalar()
-        total_orders = int(total_orders_result) if total_orders_result else 0
-        avg_order_value = total_spent / total_orders if total_orders > 0 else 0
 
         return {
             "total": total,
             "active": active,
             "inactive": inactive,
-            "with_orders": with_orders,
-            "total_spent": total_spent,
-            "total_orders": total_orders,
-            "avg_order_value": round(avg_order_value, 2),
         }
 
     def get_customer(
@@ -195,9 +177,6 @@ class AdminCustomerService:
             "customer_number": customer.customer_number,
             "marketing_consent": customer.marketing_consent,
             "preferred_language": customer.preferred_language,
-            "last_order_date": customer.last_order_date,
-            "total_orders": customer.total_orders,
-            "total_spent": float(customer.total_spent) if customer.total_spent else 0,
             "is_active": customer.is_active,
             "created_at": customer.created_at,
             "updated_at": customer.updated_at,