fix(tags): handle list input in _sync_inheritance_for_qs + recalibrate Stage 3 pins

After Stage 2's location precompute landed under Stage 3, the `locations`
list passed by `propagate_tags_on_product_sync` reached
`_sync_inheritance_for_qs` which tried to call `.only(...)` on it. Accept
either a list or a queryset.

Recalibrate V3 pins for the Stage 2 + Stage 3 compound effect:
- product_tag_add (100 locations): 123 -> 75
- product_tag_remove (100 locations): 73 -> 49
- ZAP scan import: 698 -> 661
- ZAP scan reimport, no change: 136 -> 99

Author: valentijnscholten

dojo/product/helpers.py

@@ -129,7 +129,7 @@ def _sync_inheritance_for_qs(queryset, *, target_names_per_child):
       - bulk add/remove on `tags` based on the diff
       - bulk UPDATE of `_inherited_tag_names`
     """
-    children = list(queryset.only("pk", "_inherited_tag_names"))
+    children = queryset if isinstance(queryset, list) else list(queryset.only("pk", "_inherited_tag_names"))
     if not children:
         return
 

unittests/test_tag_inheritance_perf.py

@@ -385,9 +385,9 @@ def test_baseline_product_tag_remove_propagates_to_100_locations_v3(self):
 
     # V3 location paths. Pre-Phase-A: 4532 add, 4307 remove.
     # Phase B Stage 2 + location precompute: bulk-built target-name map.
-    # Stage 3 may further drop these once JSON column replaces M2M reads.
-    EXPECTED_PRODUCT_TAG_ADD_100_LOCATIONS = 123
-    EXPECTED_PRODUCT_TAG_REMOVE_100_LOCATIONS = 73
+    # Stage 3 (JSON column) collapsed inherited_tags M2M reads further.
+    EXPECTED_PRODUCT_TAG_ADD_100_LOCATIONS = 75
+    EXPECTED_PRODUCT_TAG_REMOVE_100_LOCATIONS = 49
 
 
 @override_settings(
@@ -509,6 +509,6 @@ def test_baseline_zap_scan_reimport_no_change_v3(self):
     # when there's no work. Stages 3+4+5 (drop duplicate inherited_tags M2M)
     # will collapse the reimport cost.
     EXPECTED_ZAP_IMPORT_V2 = 700
-    EXPECTED_ZAP_IMPORT_V3 = 698
+    EXPECTED_ZAP_IMPORT_V3 = 661
     EXPECTED_ZAP_REIMPORT_NO_CHANGE_V2 = 78
-    EXPECTED_ZAP_REIMPORT_NO_CHANGE_V3 = 136
+    EXPECTED_ZAP_REIMPORT_NO_CHANGE_V3 = 99