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/routes/pages/merchant.py

@@ -50,6 +50,55 @@ async def merchant_stores_page(
     )
 
 
+@router.get("/stores/{store_id}", response_class=HTMLResponse, include_in_schema=False)
+async def merchant_store_detail_page(
+    request: Request,
+    store_id: int,
+    current_user: UserContext = Depends(get_current_merchant_from_cookie_or_header),
+    db: Session = Depends(get_db),
+):
+    """
+    Render the merchant store detail/edit page.
+
+    Shows store details and allows editing merchant-allowed fields.
+    """
+    context = get_context_for_frontend(
+        FrontendType.MERCHANT,
+        request,
+        db,
+        user=current_user,
+    )
+    context["store_id"] = store_id
+    return templates.TemplateResponse(
+        "tenancy/merchant/store-detail.html",
+        context,
+    )
+
+
+@router.get("/team", response_class=HTMLResponse, include_in_schema=False)
+async def merchant_team_page(
+    request: Request,
+    current_user: UserContext = Depends(get_current_merchant_from_cookie_or_header),
+    db: Session = Depends(get_db),
+):
+    """
+    Render the merchant team management page.
+
+    Shows team members across all stores owned by the merchant,
+    with ability to invite and manage per-store teams.
+    """
+    context = get_context_for_frontend(
+        FrontendType.MERCHANT,
+        request,
+        db,
+        user=current_user,
+    )
+    return templates.TemplateResponse(
+        "tenancy/merchant/team.html",
+        context,
+    )
+
+
 @router.get("/profile", response_class=HTMLResponse, include_in_schema=False)
 async def merchant_profile_page(
     request: Request,