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/definition.py

@@ -100,17 +100,17 @@ customers_module = ModuleDefinition(
     menus={
         FrontendType.ADMIN: [
             MenuSectionDefinition(
-                id="storeOps",
-                label_key="customers.menu.store_operations",
+                id="userManagement",
+                label_key="customers.menu.user_management",
                 icon="user-group",
-                order=40,
+                order=10,
                 items=[
                     MenuItemDefinition(
                         id="customers",
                         label_key="customers.menu.customers",
                         icon="user-group",
                         route="/admin/customers",
-                        order=20,
+                        order=40,
                     ),
                 ],
             ),