[REF] product_origin_char: simplify to template-based origin

- Move origin_text field from product.supplierinfo to product.template
- Add related field in product.product for variant access
- Remove dependency on product_main_seller
- Update views to show field near category (editable)
- Rewrite tests for new architecture
- Update all documentation (README, readme/ fragments)
- Bump version to 18.0.2.0.0

product_origin_char/models/product_template.py

@@ -1,7 +1,6 @@
 # Copyright 2026 Criptomart
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
-from odoo import api
 from odoo import fields
 from odoo import models
 
@@ -11,20 +10,5 @@ class ProductTemplate(models.Model):
 
     origin_text = fields.Char(
         string="Origin",
-        compute="_compute_origin_text",
-        store=False,
-        help="Origin text from main vendor's supplierinfo",
+        help="Origin of the product.",
     )
-
-    @api.depends("main_seller_id", "variant_seller_ids.origin_text")
-    def _compute_origin_text(self):
-        for template in self:
-            if template.main_seller_id:
-                # Find the supplierinfo record for the main seller
-                main_seller = template.main_seller_id
-                seller = template.variant_seller_ids.filtered(
-                    lambda s, ms=main_seller: s.partner_id == ms
-                )[:1]
-                template.origin_text = seller.origin_text if seller else False
-            else:
-                template.origin_text = False