[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/static/src/css/components/order-card.css

@@ -17,7 +17,8 @@
     border: 1px solid rgba(90, 103, 216, 0.12);
     border-radius: 0.75rem;
     box-shadow: 0 6px 18px rgba(28, 37, 80, 0.06);
-    transition: transform 320ms cubic-bezier(.2, .9, .2, 1), box-shadow 320ms, border-color 320ms, background 320ms;
+    transition: transform 320ms cubic-bezier(0.2, 0.9, 0.2, 1), box-shadow 320ms, border-color 320ms,
+        background 320ms;
     overflow: hidden;
     display: flex;
     flex-direction: column;
@@ -139,7 +140,7 @@
 }
 
 .eskaera-order-card .btn::before {
-    content: '';
+    content: "";
     position: absolute;
     top: 50%;
     left: 50%;