[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/tests/test_product_discovery.py

@@ -139,7 +139,8 @@ class TestProductDiscoveryUnion(TransactionCase):
         """Test discovery includes products from linked categories."""
         self.group_order.category_ids = [(4, self.category1.id)]
 
-        discovered = self.group_order.product_ids  # Computed
+        # Computed placeholder to ensure discovery logic is exercised during test setup
+        _ = self.group_order.product_ids
         # Should include cat1_product and supplier_product (both in category1)
         # Note: depends on how discovery is computed
 
@@ -346,9 +347,13 @@ class TestDeepCategoryHierarchies(TransactionCase):
         # Attempt to create circular ref may fail
         try:
             self.cat_l1.parent_id = self.cat_l5.id  # Creates loop
-        except:
-            # Expected: Odoo should prevent circular refs
-            pass
+        except Exception as exc:
+            # Expected: Odoo should prevent circular refs. Log for visibility.
+            import logging
+
+            logging.getLogger(__name__).info(
+                "Expected exception creating circular category: %s", str(exc)
+            )
 
 
 class TestEmptySourcesDiscovery(TransactionCase):