Add providers.yaml `language` / Action input `language`; prompts and
published summary/inline honor it. Soften fail-closed messaging when
models 429; prefer cohere/nvidia in the first-3 parallel set for dogfood.
Remove the optional setup-node step (still 404s as ##[error] on this
forge). Fix review.sh output writer — escaped quotes in a one-liner
caused SyntaxError after an otherwise successful publish.