Swaps the Google flash entry in the OpenRouter and Nous Portal curated
lists to the newly released gemini-3.7-flash (half the price of
3.6-flash: $0.375/M in, $1.875/M out per OpenRouter live metadata;
served on both endpoints, verified live). Also updates the OpenRouter
plugin fallback_models mirror and regenerates model-catalog.json.
Scoped to the two named providers: vertex/gemini/gmi curated lists and
aux defaults still carry 3.6-flash.
b8d9230cf2