[REF] Code quality improvements and structure fixes

- Add mypy.ini configuration to exclude migration scripts
- Rename migration files to proper snake_case (post-migration.py → post_migration.py)
- Add __init__.py to migration directories for proper Python package structure
- Add new portal access tests for website_sale_aplicoop
- Code formatting improvements (black, isort)
- Update copilot instructions and project configuration

Related to previous code quality refactoring work.

website_sale_aplicoop/migrations/18.0.1.0.0/__init__.py

@@ -0,0 +1,4 @@
+"""Make migrations folder a package so mypy maps module names correctly.
+
+Empty on purpose.
+"""

website_sale_aplicoop/migrations/18.0.1.0.2/post-migrate.py

@@ -1,9 +1,13 @@
 # Copyright 2025 Criptomart
 # License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl)
 
+import logging
+
 from odoo import SUPERUSER_ID
 from odoo import api
 
+_logger = logging.getLogger(__name__)
+
 
 def migrate(cr, version):
     """Migración para agregar soporte multicompañía.
@@ -27,5 +31,4 @@ def migrate(cr, version):
             (default_company.id,),
         )
 
-        cr.commit()
-        print(f"✓ Asignado company_id={default_company.id} a group.order")
+        _logger.info("Asignado company_id=%d a group.order", default_company.id)