fix(security): validate Nous Portal inference_base_url against host allowlist

The Nous Portal proxy adapter forwards minted ``agent_key`` bearer tokens
to whatever ``base_url`` ``resolve_nous_runtime_credentials()`` returns,
which is read directly from the refresh / agent-key-mint response and
persisted to ``~/.hermes/auth.json``. With no validation beyond a
trailing-slash strip, a poisoned URL (Portal-side MITM, or local write
to auth.json) gets forwarded the legitimate bearer on every subsequent
proxy request — exfiltrating the user's inference budget and opening a
response-injection channel back into the IDE / chat client.

Add ``_validate_nous_inference_url_from_network()`` in ``hermes_cli.auth``:
an https + host-allowlist check that returns None for anything outside
``inference-api.nousresearch.com``, so callers fall back to the
documented default rather than ship the bearer to an attacker.

This commit wires the validator into the proxy adapter at
``nous_portal.py``. A follow-up commit wires it into the four refresh /
mint sites in ``auth.py`` so the poisoned URL never lands in auth.json
in the first place.

The env-var override path (``NOUS_INFERENCE_BASE_URL``) bypasses
validation by design — that's the documented staging/dev escape hatch
and the env source is already trusted (the user set it themselves).

Co-authored-by: memosr <mehmet.sr35@gmail.com>

hermes_cli/proxy/adapters/nous_portal.py

@@ -27,6 +27,7 @@ from hermes_cli.auth import (
     _quarantine_nous_oauth_state,
     _quarantine_nous_pool_entries,
     _save_auth_store,
+    _validate_nous_inference_url_from_network,
     _write_shared_nous_state,
     resolve_nous_runtime_credentials,
 )
@@ -137,7 +138,10 @@ class NousPortalAdapter(UpstreamAdapter):
                     "Try `hermes login nous` to re-authenticate."
                 )
 
-            base_url = refreshed.get("base_url") or DEFAULT_NOUS_INFERENCE_URL
+            base_url = (
+                _validate_nous_inference_url_from_network(refreshed.get("base_url"))
+                or DEFAULT_NOUS_INFERENCE_URL
+            )
             base_url = base_url.rstrip("/")
 
             return UpstreamCredential(