[ADD] website_sale_aplicoop: serve Eskaera per website

A co-op can run the plain shop on one website and the group orders on another,
but routes are registered process-wide: every /eskaera page answered on every
website of the database, and Odoo had already copied the Eskaera menu to all of
them.

`website.eskaera_enabled` decides which websites serve it, on by default so
installing changes nothing. It reaches the settings screen through `website_id`,
so it follows the website selector there. Where it is off the routes raise
NotFound and the menu is hidden.

The menu is hidden rather than deleted, by extending `_compute_visible`. That
keeps the record and any manual rename or reordering, so switching the feature
back on restores it as it was.

Note that a JSON route reports the 404 inside the JSON-RPC payload and still
answers HTTP 200; that is the transport, not a hole in the guard, and a test
pins it so the next reader does not take it for one.

The three remaining settings (lazy loading, products per page, low stock
threshold) are still `config_parameter`, so they stay global to the database.
Two websites share their values.

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

website_sale_aplicoop/models/res_config_settings.py

@@ -7,6 +7,13 @@ from odoo import models
 class ResConfigSettings(models.TransientModel):
     _inherit = "res.config.settings"
 
+    # Per website: a co-op can run the plain shop on one and Eskaera on
+    # another. The settings below are still global to the database.
+    eskaera_enabled = fields.Boolean(
+        related="website_id.eskaera_enabled",
+        readonly=False,
+    )
+
     eskaera_lazy_loading_enabled = fields.Boolean(
         string="Enable Lazy Loading",
         config_parameter="website_sale_aplicoop.lazy_loading_enabled",