Document the performance-toolkit fixture generator conflict

[jeanmarcos-dev]

Documents a conflict between this module and the performance toolkit, found while running the
stress suite against a 2.4.9 install.

setup:performance:generate-fixtures aborts with
The entity ID field for the "queue_message" table wasn't found whenever
Magento_InventoryStockVisualizer is enabled.

The chain:

1. The fixture generator saves one template product and uses SqlCollector to capture, through
   the DB profiler, every INSERT INTO that save emits — it assumes each captured table belongs
   to the product entity.
2. Saving the template writes source items, which fires the supply-seam plugin
   (PurgeOnSourceItemsSave) and publishes a purge message onto the database-backed queue, so
   INSERT INTO queue_message lands in that set.
3. EntityGenerator::getEntityIdField() then looks for a foreign key from queue_message to
   catalog_product_entity, finds none, and throws.

Confirmed by disabling the module: the same profile that aborted then generated 1600
product_dynamic_* products in 22s. Re-enabling it and recompiling DI leaves the catalog intact,
so the workaround is limited to the generation window.

This is not a regression from the upstream sync. The failure was initially suspected to come from
ACP2E-4349 (which dropped the pinned queue="…" publisher attribute), so that was tested
directly: restoring the attribute on the three queue_publisher.xml files reproduced the abort
identically. The trigger is the purge publish itself, not which queue name it targets.

Fixture generation is the only thing affected — storefront and admin behaviour are untouched. Any
module publishing to the database-backed queue during a product save hits the same generator
limitation, so the note is worded accordingly.

Documentation only; no code changes. The QA gate reports no PHP files to check.