fix: loyalty module end-to-end — merchant route, store menus, sidebar, API error handling

- Add merchant loyalty overview route and template (was 404)
- Fix store loyalty route paths to match menu URLs (/{store_code}/loyalty/...)
- Add loyalty rewards card to storefront account dashboard
- Fix merchant overview to resolve merchant via get_merchant_for_current_user_page
- Fix store login to use store's primary platform for JWT token (interim fix)
- Fix apiClient to attach status/errorCode to thrown errors (fixes error.status
  checks in 12+ JS files — loyalty settings, terminal, email templates, etc.)
- Hide "Add Product" sidebar button when catalog module is not enabled
- Add proposal doc for proper platform detection in store login flow

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/tenancy/routes/api/store_auth.py

@@ -111,10 +111,27 @@ def store_login(
         f"for store {store.store_code} as {store_role}"
     )
 
-    # Get platform from URL context (middleware-detected)
-    platform = get_current_platform(request)
-    platform_id = platform.id if platform else None
-    platform_code = platform.code if platform else None
+    # Resolve platform from the store's primary platform link.
+    # Middleware-detected platform is unreliable for API paths on localhost
+    # (e.g., /api/v1/store/auth/login defaults to "main" instead of the store's platform).
+    platform_id = None
+    platform_code = None
+    if store:
+        from app.modules.core.services.menu_service import menu_service
+        from app.modules.tenancy.services.platform_service import platform_service
+
+        primary_pid = menu_service.get_store_primary_platform_id(db, store.id)
+        if primary_pid:
+            plat = platform_service.get_platform_by_id(db, primary_pid)
+            if plat:
+                platform_id = plat.id
+                platform_code = plat.code
+
+    if platform_id is None:
+        # Fallback to middleware-detected platform
+        platform = get_current_platform(request)
+        platform_id = platform.id if platform else None
+        platform_code = platform.code if platform else None
 
     # Create store-scoped access token with store information
     token_data = auth_service.auth_manager.create_access_token(