fix: sync never changes product map state from mapped

Price conflicts and sync errors were setting woo.product.map state to
'conflict'/'error', making products disappear from the mapped list.
Conflicts are now tracked only in woo.conflict model. Map state stays
'mapped' as long as the product link exists.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

fusion-woo-odoo/fusion_woocommerce/models/woo_instance.py

@@ -793,7 +793,7 @@ class WooInstance(models.Model):
                         'woo_value': str(wc_price),
                         'company_id': self.company_id.id,
                     })
-                    pm.state = 'conflict'
+                    # Keep state as mapped — conflict is tracked separately
                     self._log_sync(
                         'product', 'woo_to_odoo', pm.product_id.display_name,
                         'conflict', f'Price conflict: Odoo=${odoo_price}, WC=${wc_price}',
@@ -821,7 +821,7 @@ class WooInstance(models.Model):
                     "Product price sync failed for %s (WC#%s): %s",
                     pm.product_id.display_name, pm.woo_product_id, e,
                 )
-                pm.state = 'error'
+                # Don't change map state on sync errors — keep it mapped
                 self._log_sync(
                     'product', 'odoo_to_woo',
                     pm.product_id.display_name, 'failed', str(e),