[FIX] estate: use context_today to avoid timezone issues

- use context_today to avoid timezone issues
- also inline the reference date calculation for clarity and remove the corresponding function

Author: robal-odoo

estate/models/estate_property_offer.py

@@ -29,11 +29,13 @@ class EstatePropertyOffer(models.Model):
     @api.depends("create_date", "validity")
     def _compute_deadline(self) -> None:
         for record in self:
-            record.date_deadline = _get_reference_date(record) + relativedelta(days=record.validity)
+            ref_date = fields.Date.context_today(self) if not record.create_date else record.create_date.date()
+            record.date_deadline = ref_date + relativedelta(days=record.validity)
 
     def _inverse_deadline(self) -> None:
         for record in self:
-            record.validity = (record.date_deadline - _get_reference_date(record)).days
+            ref_date = fields.Date.context_today(self) if not record.create_date else record.create_date.date()
+            record.validity = (record.date_deadline - ref_date).days
 
     # CRUD overrides
     @api.model
@@ -70,7 +72,3 @@ def action_refuse(self) -> bool:
         "CHECK(price > 0)",
         "An offer's price must be strictly greater than 0.",
     )
-
-
-def _get_reference_date(offer: EstatePropertyOffer) -> date:
-    return fields.Date.today() if not offer.create_date else offer.create_date.date()