extractPersonalization() now reads both 'attributes' and 'custom_fields' fields
from the shopPRO API response, joining non-empty values with newline separator.
Previously only custom_fields was imported, causing product attributes like
"Woreczek jutowy", "Kolor koperty", "Zakrętka" to be lost during sync.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>