Fix: improve performance by not loading REST controllers on frontend

[rami-elementor]

Code snippets registers 5 REST controllers on every request (frontend included).

Why it matters? Because it registers rest_api_init hooks on frontend requests where they will never fire (REST requests go through a separate path).

These five REST controller instances are created on every request, each adding an add_action('rest_api_init', ...) hook. On pure frontend page loads, rest_api_init never fires, so the routes are never registered — but the constructor + hook registration still runs.

The PR defers REST controller instantiation — wrap the 5 REST controllers in a single rest_api_init callback that creates them lazily. Saves ~5 object constructions + hook registrations on frontend.