OpenCode Go's /v1/models endpoint returns models from the full public catalog that
are NOT enabled on the Go tier; selecting any such probe-only model 404s
('model not found') when the chat request is sent. get_available_models now skips
the live probe for opencode-go (bare branch) so the next `if not raw_models` falls
through to the curated static _PROVIDER_MODELS['opencode-go'] list — the actual
Go-tier models. Narrow, provider-scoped; no other provider affected.
Contributor stage; gate-pass. Co-authored-by: webtecnica <webtecnica@users.noreply.github.com>
