Fix normalized quantity basis

pm/data-model.org

@@ -344,3 +344,9 @@ Notes:
 - review/link decisions should apply at the `normalized_item_id` level, then fan out to all purchase rows sharing that id.
 
 * /
+Normalized quantity is deterministic and conservative:
+- if `qty * pack_qty * size_value` is available, use that total with `size_unit`
+- else if count basis is explicit, use `qty * pack_qty` with unit `count`
+- else if `measure_type` is `each`, use `qty each`
+- else leave both fields blank
+- no hidden unit conversion is applied inside normalization; values stay in their parsed units such as `oz`, `lb`, `qt`, or `count`