Why: TestMaterialIntakeAttachmentOnlyLifecycle flaked when waiting on
systemTexts; deliverNotices runs before defer materialKeyRelease, so
done-dedup still saw the in-memory key and returned pending.
Evidence: go test ./internal/runmgr/ -run TestMaterialIntakeAttachmentOnlyLifecycle -count=20
Impact: Aligns the wait with materialExisting gates; no production change.
Refs: fix/material-intake-lifecycle-flake
Co-authored-by: Cursor <cursoragent@cursor.com>