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>

tests/agent/test_usage_pricing.py

@@ -192,6 +192,32 @@ def test_custom_endpoint_models_api_pricing_is_supported(monkeypatch):
     assert float(entry.output_cost_per_million) == 2.0
 
 
+def test_nous_portal_pricing_preserves_vendor_prefixed_model_ids(monkeypatch):
+    seen = {}
+
+    def _fake_fetch_endpoint_model_metadata(base_url, api_key=None):
+        seen["base_url"] = base_url
+        return {
+            "openai/gpt-5.5-pro": {
+                "pricing": {
+                    "prompt": "0.000025",
+                    "completion": "0.000125",
+                }
+            }
+        }
+
+    monkeypatch.setattr(
+        "agent.usage_pricing.fetch_endpoint_model_metadata",
+        _fake_fetch_endpoint_model_metadata,
+    )
+
+    entry = get_pricing_entry("openai/gpt-5.5-pro", provider="nous")
+
+    assert seen["base_url"] == "https://inference-api.nousresearch.com/v1"
+    assert float(entry.input_cost_per_million) == 25.0
+    assert float(entry.output_cost_per_million) == 125.0
+
+
 def test_deepseek_v4_pro_pricing_entry_exists():
     """Regression test: deepseek-v4-pro must have a pricing entry.