bug(events): upsert-post permission denial on merged-duplicate reimport in CI since #3933 #3944

Bug

DataMachineEvents\Tests\Unit\EventUpsertTest::test_merged_duplicate_whose_winner_is_gone_restores_on_reimport fails in CI (Homeboy (review test), data-machine-events) on every PR opened since #3933 landed (#3939, #3940, #3942). None of those PRs touch upsert:

Failed asserting that false is true.
{"success":false,"error":"Ability \"datamachine/upsert-post\" does not have necessary permission.",
 "tool_name":"DataMachineEvents\\Steps\\Upsert\\Events\\EventUpsert","error_code":"ability_invalid_permissions",...}

The failing step is the reimport of the loser parameters, after EventMergeHelper::merge( $winner, $loser ) and wp_trash_post( $winner ).

Observations

• The suspect is 5f672d8, "fix(abilities): enforce per-object post capabilities in upsert-post (fix(abilities): enforce per-object post capabilities in upsert-post #3933)", merged 2026-11-12. The data-machine-events CI suite hasn't run on main since then, so there's no baseline (the digest says "baseline artifact unavailable").
• The test passes locally with the native MariaDB harness (homeboy review test data-machine-events --placement local -- --filter=test_merged_duplicate). It only fails in the CI environment (multisite Playground). It may depend on the DB engine or on test order, but the error is a capability denial from UpsertPostAbility::check_permission() / authorize_request().
• The current user in EventUpsertTestCase::setUp is a site administrator, not a super admin. On multisite, per-object checks that resolve to the trashed winner or to a merged-redirect target may deny it.

Why it matters

If #3933 makes legitimate reimports of merged duplicates fail permission checks, production pipelines could hit the same ability_invalid_permissions when re-scraping a merged event whose winner was trashed.

Done looks like

• Identify which object authorize_request() checks in this flow and why it's denied in CI.
• Fix either the capability resolution (upstream in data-machine core, if it's a real regression) or the test setup (if it's a test-environment artifact).
• Make the data-machine-events CI suite green on main.