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/orders/tests/unit/test_customer_order_stats.py

@@ -0,0 +1,84 @@
+# tests/unit/models/test_customer_order_stats.py
+"""Unit tests for CustomerOrderStats model."""
+
+import pytest
+from sqlalchemy.exc import IntegrityError
+
+from app.modules.orders.models.customer_order_stats import CustomerOrderStats
+
+
+@pytest.mark.unit
+@pytest.mark.database
+class TestCustomerOrderStatsModel:
+    """Test CustomerOrderStats model."""
+
+    def test_create_stats(self, db, test_store, test_customer):
+        """Test creating customer order stats."""
+        stats = CustomerOrderStats(
+            store_id=test_store.id,
+            customer_id=test_customer.id,
+            total_orders=3,
+            total_spent_cents=15000,
+        )
+        db.add(stats)
+        db.commit()
+        db.refresh(stats)
+
+        assert stats.id is not None
+        assert stats.store_id == test_store.id
+        assert stats.customer_id == test_customer.id
+        assert stats.total_orders == 3
+        assert stats.total_spent_cents == 15000
+
+    def test_default_values(self, db, test_store, test_customer):
+        """Test default values for stats."""
+        stats = CustomerOrderStats(
+            store_id=test_store.id,
+            customer_id=test_customer.id,
+        )
+        db.add(stats)
+        db.commit()
+        db.refresh(stats)
+
+        assert stats.total_orders == 0
+        assert stats.total_spent_cents == 0
+        assert stats.last_order_date is None
+        assert stats.first_order_date is None
+
+    def test_unique_constraint(self, db, test_store, test_customer):
+        """Test unique constraint on store_id + customer_id."""
+        stats1 = CustomerOrderStats(
+            store_id=test_store.id,
+            customer_id=test_customer.id,
+            total_orders=1,
+        )
+        db.add(stats1)
+        db.commit()
+
+        stats2 = CustomerOrderStats(
+            store_id=test_store.id,
+            customer_id=test_customer.id,
+            total_orders=2,
+        )
+        db.add(stats2)
+        with pytest.raises(IntegrityError):
+            db.commit()
+
+    def test_update_stats(self, db, test_store, test_customer):
+        """Test updating existing stats."""
+        stats = CustomerOrderStats(
+            store_id=test_store.id,
+            customer_id=test_customer.id,
+            total_orders=1,
+            total_spent_cents=5000,
+        )
+        db.add(stats)
+        db.commit()
+
+        stats.total_orders = 2
+        stats.total_spent_cents = 12000
+        db.commit()
+        db.refresh(stats)
+
+        assert stats.total_orders == 2
+        assert stats.total_spent_cents == 12000