Design Receiver From Intent

Select catalog parts for a design intent, then compute through the engine.

The sibling of the route above, not a widening of it. POST /api/receiver is the pure-engine path and 422s without explicit stages — a contract its tests pin. A caller that only knows "X-band, 10 MHz, 12 dB SNR" has no stages to give, which is exactly the standalone designer's case.

Selection reuses assemble_receiver, the SAME function the design_rf_receiver agent tool calls, so the page and the assistant can never disagree about which part fills a slot. Slots no catalog part covers come back in needsPartFlags rather than filled with an assumed component.

Rate-limited harder than the pure-engine route (30/min vs 60): this one hits the component database and runs the per-slot scoring agents.