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/tenancy/static/store/js/login.js

@@ -8,6 +8,27 @@
 // Create custom logger for store login page
 const storeLoginLog = window.LogConfig.createLogger('STORE-LOGIN');
 
+function languageSelector(currentLang, enabledLanguages) {
+    return {
+        currentLang: currentLang || 'fr',
+        languages: enabledLanguages || ['en', 'fr', 'de', 'lb'],
+        async setLanguage(lang) {
+            if (lang === this.currentLang) return;
+            try {
+                // noqa: JS-008 - Login page has no apiClient; raw fetch is intentional
+                await fetch('/api/v1/platform/language/set', {
+                    method: 'POST',
+                    headers: { 'Content-Type': 'application/json' },
+                    body: JSON.stringify({ language: lang }),
+                });
+                window.location.reload();
+            } catch (error) {
+                storeLoginLog.error('Failed to set language:', error);
+            }
+        },
+    };
+}
+
 function storeLogin() {
     return {
         credentials: {
@@ -159,6 +180,7 @@ function storeLogin() {
         },
 
         // Forgot password state
+        rememberMe: false,
         showForgotPassword: false,
         forgotPasswordEmail: '',
         forgotPasswordLoading: false,

app/modules/tenancy/static/store/js/settings.js

@@ -39,7 +39,6 @@ function storeSettings() {
             { id: 'invoices', label: 'Invoices', icon: 'document-text' },
             { id: 'branding', label: 'Branding', icon: 'color-swatch' },
             { id: 'domains', label: 'Domains', icon: 'globe-alt' },
-            { id: 'api', label: 'API & Payments', icon: 'key' },
             { id: 'notifications', label: 'Notifications', icon: 'bell' },
             { id: 'email', label: 'Email', icon: 'mail' }
         ],