Add Products page backed by the CRM products API + storefront catalog picker

- New Products page (merchant.products.*) with full CRUD proxied to the Ladill
  CRM products API via a new CrmClient + config/crm.php (owner-scoped, type=product).
- Sidebar gains a Products entry.
- The new storefront form loads the merchant's catalog: each shop/menu section
  gets an "Add from products…" picker that drops a CRM product in as an item
  (name, price, description). Catalog fetch is resilient — empty if CRM is down.

Wires CRM_API_URL + CRM_API_KEY_MERCHANT on the merchant env (matches CRM).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

config/crm.php

@@ -0,0 +1,7 @@
+<?php
+
+return [
+    'url' => rtrim((string) env('CRM_API_URL', 'https://crm.ladill.com/api'), '/'),
+    'key' => env('CRM_API_KEY_MERCHANT'),
+    'default_currency' => env('CRM_DEFAULT_CURRENCY', 'GHS'),
+];