fix(eam): leave deleted apps out of GET /apps

Deleting an app that ever had instances only retires its specification in
SRM, and SRM's list still returns retired ones. GET /apps showed the app after
DELETE /apps/{appId} had answered 204, while GET /apps/{appId} said 404.

The list now skips a specification whose registration here is marked deleted,
which is the same thing the single-app read goes by. Specifications OEG never
registered are listed as before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>