fix: custom endpoint model validation + better /model error messages

- Custom endpoints can serve any model, so skip validation for
  provider='custom' in validate_requested_model(). Previously it
  would reject any model name since there's no static catalog or
  live API to check against.
- Show clear setup instructions when switching to custom endpoint
  without OPENAI_BASE_URL/OPENAI_API_KEY configured.
- Added curated model lists for Nous Portal and OpenAI Codex to
  _PROVIDER_MODELS so /model shows their available models.

cli.py

@@ -2795,7 +2795,11 @@ class HermesCLI:
                         base_url_for_probe = runtime.get("base_url", "")
                     except Exception as e:
                         provider_label = _PROVIDER_LABELS.get(target_provider, target_provider)
-                        print(f"(>_<) Could not resolve credentials for provider '{provider_label}': {e}")
+                        if target_provider == "custom":
+                            print(f"(>_<) Custom endpoint not configured. Set OPENAI_BASE_URL and OPENAI_API_KEY,")
+                            print(f"      or run: hermes setup → Custom OpenAI-compatible endpoint")
+                        else:
+                            print(f"(>_<) Could not resolve credentials for provider '{provider_label}': {e}")
                         print(f"(^_^) Current model unchanged: {self.model}")
                         return True
 

hermes_cli/models.py

@@ -276,6 +276,15 @@ def validate_requested_model(
             "message": "Model names cannot contain spaces.",
         }
 
+    # Custom endpoints can serve any model — skip validation
+    if normalized == "custom":
+        return {
+            "accepted": True,
+            "persist": True,
+            "recognized": False,
+            "message": None,
+        }
+
     # Probe the live API to check if the model actually exists
     api_models = fetch_api_models(api_key, base_url)