feat(#44): Add sample_type_product_id field to StockLot model

- Added sample_type_product_id Many2one field to reference sample type products
- Kept container_type field for backward compatibility (marked as legacy)
- Added @api.onchange method to synchronize fields
- Added get_container_name() method to retrieve container name from either field

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

lims_management/models/stock_lot.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-from odoo import models, fields
+from odoo import models, fields, api
 
 class StockLot(models.Model):
     _inherit = 'stock.lot'
@@ -26,7 +26,14 @@ class StockLot(models.Model):
         ('swab', 'Swab'),
         ('urine', 'Urine Container'),
         ('other', 'Other')
-    ], string='Container Type')
+    ], string='Container Type (Legacy)', help='Deprecated field, use sample_type_product_id instead')
+    
+    sample_type_product_id = fields.Many2one(
+        'product.template',
+        string='Tipo de Muestra',
+        domain="[('is_sample_type', '=', True)]",
+        help="Producto que representa el tipo de contenedor/muestra"
+    )
 
     collector_id = fields.Many2one(
         'res.users', 
@@ -57,3 +64,28 @@ class StockLot(models.Model):
 
     def action_dispose(self):
         self.write({'state': 'disposed'})
+    
+    @api.onchange('sample_type_product_id')
+    def _onchange_sample_type_product_id(self):
+        """Synchronize container_type when sample_type_product_id changes"""
+        if self.sample_type_product_id:
+            # Try to map product name to legacy container type
+            product_name = self.sample_type_product_id.name.lower()
+            if 'suero' in product_name or 'serum' in product_name:
+                self.container_type = 'serum_tube'
+            elif 'edta' in product_name:
+                self.container_type = 'edta_tube'
+            elif 'hisopo' in product_name or 'swab' in product_name:
+                self.container_type = 'swab'
+            elif 'orina' in product_name or 'urine' in product_name:
+                self.container_type = 'urine'
+            else:
+                self.container_type = 'other'
+    
+    def get_container_name(self):
+        """Get container name from product or legacy field"""
+        if self.sample_type_product_id:
+            return self.sample_type_product_id.name
+        elif self.container_type:
+            return dict(self._fields['container_type'].selection).get(self.container_type)
+        return 'Unknown'