fix(model): require confirmation for expensive model selections

Rebased onto current main and re-ported across the restructured
surfaces: model flows now thread confirm_provider/base_url/api_key
through hermes_cli/model_setup_flows.py, the Discord picker lives in
plugins/platforms/discord/adapter.py, and the web dashboard picker
applies chat-mode switches via config.set so the expensive-model
confirmation can ride the response.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

agent/usage_pricing.py

@@ -13,6 +13,7 @@ DEFAULT_PRICING = {"input": 0.0, "output": 0.0}
 
 _ZERO = Decimal("0")
 _ONE_MILLION = Decimal("1000000")
+_NOUS_DEFAULT_BASE_URL = "https://inference-api.nousresearch.com/v1"
 
 CostStatus = Literal["actual", "estimated", "included", "unknown"]
 CostSource = Literal[
@@ -570,6 +571,8 @@ def resolve_billing_route(
         return BillingRoute(provider="openai-codex", model=model, base_url=base_url or "", billing_mode="subscription_included")
     if provider_name == "openrouter" or base_url_host_matches(base_url or "", "openrouter.ai"):
         return BillingRoute(provider="openrouter", model=model, base_url=base_url or "", billing_mode="official_models_api")
+    if provider_name == "nous" or base_url_host_matches(base_url or "", "inference-api.nousresearch.com"):
+        return BillingRoute(provider="nous", model=model, base_url=base_url or _NOUS_DEFAULT_BASE_URL, billing_mode="official_models_api")
     if provider_name == "anthropic":
         return BillingRoute(provider="anthropic", model=model.split("/")[-1], base_url=base_url or "", billing_mode="official_docs_snapshot")
     if provider_name == "openai":