fix: add missing db argument to get_admin_context calls

The get_admin_context function signature changed to require db as
the second argument, but many admin route handlers were still using
the old signature (request, current_user).

Updated all occurrences across modules:
- core, catalog, dev_tools, inventory, customers, messaging
- billing, tenancy, monitoring, analytics, orders, marketplace

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/modules/inventory/routes/pages/admin.py

@@ -36,5 +36,5 @@ async def admin_inventory_page(
     """
     return templates.TemplateResponse(
         "inventory/admin/inventory.html",
-        get_admin_context(request, current_user),
+        get_admin_context(request, db, current_user),
     )