[ADD] website_sale_disable_cart: extract cart restriction from website_sale_aplicoop

The "shop as a read-only catalog" behaviour lived inside website_sale_aplicoop,
so every site that wanted the eskaera flow also lost the standard cart. It now
ships as its own installable addon, with the redirect target configurable
instead of hardcoded to /eskaera.

- website_sale_disable_cart: hides the cart UI (12 header styles + the product
  card quick-add) and overrides the standard cart endpoints. Redirect URL is
  configurable in Website settings (default /shop); only site-internal paths are
  accepted, so a misconfigured value cannot turn the shop into an open redirect
  nor loop back into a disabled route.
- Fixes carried over from the original code: /shop/cart/quantity is the Odoo 18
  path (it was /shop/cart_quantity, which never matched), the boxed, sidebar and
  sales two/three/four headers were not covered (the cart link stayed visible on
  them), and the routes now override the standard methods instead of registering
  duplicate ones.
- website_sale_aplicoop 18.0.1.12.0: drops the view file and the four redirect
  routes; installing it no longer touches the standard shop.

Upgrade order matters: update website_sale_aplicoop first, then install
website_sale_disable_cart in a second Odoo run — both use the same XPaths and
obsolete records are only cleaned up at the end of a run.

Tests: 8/8 in website_sale_disable_cart, aplicoop unaffected (its 2 failures
predate this change). Verified live on a DB clone: /shop/cart returns 303 to the
configured URL and no cart markup remains on /shop.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

website_sale_disable_cart/LICENSE.txt

@@ -0,0 +1,56 @@
+GNU AFFERO GENERAL PUBLIC LICENSE
+Version 3, 19 November 2007
+
+Website Sale - Aplicoop
+Copyright 2025 Criptomart SL
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU Affero General Public License as
+published by the Free Software Foundation, either version 3 of the
+License, or (at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Affero General Public License for more details.
+
+You should have received a copy of the GNU Affero General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+---
+
+FULL LICENSE TEXT
+=================
+
+For the complete AGPL-3 license text, see:
+https://www.gnu.org/licenses/agpl-3.0.html
+
+---
+
+SUMMARY OF RIGHTS
+=================
+
+When you distribute a modified version under AGPL-3, you must:
+
+1. Keep the same license (AGPL-3)
+2. Provide a copy of the license with your distribution
+3. State what changes you made
+4. Include the original copyright notices
+5. If distributed over a network, provide source code access
+
+Detailed information: https://www.gnu.org/licenses/agpl-3.0-standalone.html
+
+---
+
+ATTRIBUTION
+===========
+
+This module was developed by: Criptomart SL
+Website: https://criptomart.net
+
+Original inspiration: Aplicoop project
+https://sourceforge.net/projects/aplicoop/
+
+---
+
+This file is part of the Website Sale - Aplicoop module for Odoo.