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/loyalty/services/loyalty_onboarding.py

@@ -26,8 +26,8 @@ class LoyaltyOnboardingProvider:
         return [
             OnboardingStepDefinition(
                 key="loyalty.create_program",
-                title_key="onboarding.loyalty.create_program.title",
-                description_key="onboarding.loyalty.create_program.description",
+                title_key="loyalty.onboarding.create_program.title",
+                description_key="loyalty.onboarding.create_program.description",
                 icon="gift",
                 route_template="/store/{store_code}/loyalty/programs",
                 order=300,