fix(migration): Synchronize related fields (area_id, category) from ows.machine to maintenance.equipment

The related fields in maintenance.equipment with store=True were not automatically
synchronized during migration. Added explicit SQL UPDATE statements to copy values:
- ows_area_id from area_id
- ows_category from category

This ensures the maintenance.equipment records have all the OWS-specific data
from the original ows.machine records after migration.

open_workshop_base/migrations/18.0.1.0.4/post-migration.py

@@ -99,7 +99,30 @@ def migrate(cr, version):
         except Exception as e:
             _logger.error(f"Failed to migrate machine {m_id}: {e}")
     
-    # 3. Validierung
+    # 3. Synchronisiere related fields von ows.machine nach maintenance.equipment
+    _logger.info("Synchronizing related fields (area_id, category) to maintenance.equipment...")
+    
+    cr.execute("""
+        UPDATE maintenance_equipment me
+        SET ows_area_id = om.area_id
+        FROM ows_machine om
+        WHERE om.equipment_id = me.id
+        AND om.area_id IS NOT NULL
+    """)
+    synced_areas = cr.rowcount
+    _logger.info(f"✅ Synchronized {synced_areas} area_id values")
+    
+    cr.execute("""
+        UPDATE maintenance_equipment me
+        SET ows_category = om.category
+        FROM ows_machine om
+        WHERE om.equipment_id = me.id
+        AND om.category IS NOT NULL
+    """)
+    synced_categories = cr.rowcount
+    _logger.info(f"✅ Synchronized {synced_categories} category values")
+    
+    # 4. Validierung
     cr.execute("SELECT COUNT(*) FROM ows_machine WHERE equipment_id IS NULL")
     remaining = cr.fetchone()[0]
     
@@ -109,3 +132,4 @@ def migrate(cr, version):
         _logger.info(f"✅ Successfully migrated {migrated_count} machines to equipment")
     
     _logger.info("Post-migration completed")
+