Pipeline execution returns an honest unavailable response
Multi-modal pipeline runs no longer return simulated prices as if they were computed; authorized execution reports 501 until real stages are wired, while pipeline discovery keeps working.
The multi-modal pipeline endpoints executed a simulation and returned it as a successful result: a price, a confidence, and per-stage cost and latency numbers, all produced from constants, with only a simulated field to mark them. A marker in one field does not make a fabricated success honest, so both pipeline execution endpoints now return 501 with code: pipeline_execution_unavailable instead of a simulated price. The protected endpoint first checks credentials and returns 401 when they are missing or invalid; its 501 response follows successful authentication. The public endpoint needs no credentials.
Discovery is unaffected: listing the reference pipelines (and, on the authenticated route, the stage catalogue) still works, so you can see what the network will run once execution is wired. Single-price computation is unchanged and available today.
The consumer price-check page and the dashboard pipeline console now show a clear "not available yet" notice rather than a fabricated recommendation.