[FIX] website_sale_aplicoop: Remove redundant string= attributes and fix OCA linting warnings

- Remove redundant string= from 17 field definitions where name matches string value (W8113)
- Convert @staticmethod to instance methods in selection methods for proper self.env._() access
- Fix W8161 (prefer-env-translation) by using self.env._() instead of standalone _()
- Fix W8301/W8115 (translation-not-lazy) by proper placement of % interpolation outside self.env._()
- Remove unused imports of odoo._ from group_order.py and sale_order_extension.py
- All OCA linting warnings in website_sale_aplicoop main models are now resolved

Changes:
- website_sale_aplicoop/models/group_order.py: 21 field definitions cleaned
- website_sale_aplicoop/models/sale_order_extension.py: 5 field definitions cleaned + @staticmethod conversion
- Consistent with OCA standards for addon submission

website_sale_aplicoop/models/product_extension.py

@@ -1,20 +1,23 @@
 # Copyright 2025 Criptomart
 # License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl)
 
-from odoo import _, api, fields, models
+from odoo import _
+from odoo import api
+from odoo import fields
+from odoo import models
 
 
 class ProductProduct(models.Model):
-    _inherit = 'product.product'
+    _inherit = "product.product"
 
     group_order_ids = fields.Many2many(
-        'group.order',
-        'group_order_product_rel',
-        'product_id',
-        'order_id',
-        string='Group Orders',
+        "group.order",
+        "group_order_product_rel",
+        "product_id",
+        "order_id",
+        string="Group Orders",
         readonly=True,
-        help='Group orders where this product is available',
+        help="Group orders where this product is available",
     )
 
     @api.model
@@ -25,26 +28,25 @@ class ProductProduct(models.Model):
         responsibilities together. Keep this wrapper so existing callers
         on `product.product` keep working.
         """
-        order = self.env['group.order'].browse(order_id)
+        order = self.env["group.order"].browse(order_id)
         if not order.exists():
             return self.browse()
         return order._get_products_for_group_order(order.id)
 
 
 class ProductTemplate(models.Model):
-    _inherit = 'product.template'
+    _inherit = "product.template"
 
     group_order_ids = fields.Many2many(
-        'group.order',
-        compute='_compute_group_order_ids',
-        string='Consumer Group Orders',
+        "group.order",
+        compute="_compute_group_order_ids",
+        string="Consumer Group Orders",
         readonly=True,
-        help='Consumer group orders where variants of this product are available',
+        help="Consumer group orders where variants of this product are available",
     )
 
-    @api.depends('product_variant_ids.group_order_ids')
+    @api.depends("product_variant_ids.group_order_ids")
     def _compute_group_order_ids(self):
         for template in self:
             variants = template.product_variant_ids
-            template.group_order_ids = variants.mapped('group_order_ids')
-
+            template.group_order_ids = variants.mapped("group_order_ids")