feat: add Nous Portal API key provider (#644)

Add support for using Nous Portal via a direct API key, mirroring
how OpenRouter and other API-key providers work. This gives users a
simpler alternative to the OAuth device-code flow when they already
have a Nous API key.

Changes:
- Add 'nous-api' to PROVIDER_REGISTRY as an api_key provider
  pointing to https://inference-api.nousresearch.com/v1
- Add NOUS_API_KEY and NOUS_BASE_URL to OPTIONAL_ENV_VARS
- Add NOUS_API_BASE_URL / NOUS_API_CHAT_URL to hermes_constants
- Add 'Nous Portal API key' as first option in setup wizard
- Add provider aliases (nous_api, nousapi, nous-portal-api)
- Add test for nous-api runtime provider resolution

Closes #644

tests/test_runtime_provider_resolution.py

@@ -158,6 +158,29 @@ def test_custom_endpoint_auto_provider_prefers_openai_key(monkeypatch):
     assert resolved["api_key"] == "sk-vllm-key"
 
 
+def test_resolve_runtime_provider_nous_api(monkeypatch):
+    """Nous Portal API key provider resolves via the api_key path."""
+    monkeypatch.setattr(rp, "resolve_provider", lambda *a, **k: "nous-api")
+    monkeypatch.setattr(
+        rp,
+        "resolve_api_key_provider_credentials",
+        lambda pid: {
+            "provider": "nous-api",
+            "api_key": "nous-test-key",
+            "base_url": "https://inference-api.nousresearch.com/v1",
+            "source": "NOUS_API_KEY",
+        },
+    )
+
+    resolved = rp.resolve_runtime_provider(requested="nous-api")
+
+    assert resolved["provider"] == "nous-api"
+    assert resolved["api_mode"] == "chat_completions"
+    assert resolved["base_url"] == "https://inference-api.nousresearch.com/v1"
+    assert resolved["api_key"] == "nous-test-key"
+    assert resolved["requested_provider"] == "nous-api"
+
+
 def test_resolve_requested_provider_precedence(monkeypatch):
     monkeypatch.setenv("HERMES_INFERENCE_PROVIDER", "nous")
     monkeypatch.setattr(rp, "_get_model_config", lambda: {"provider": "openai-codex"})