fix(aux): reset auxiliary_is_nous flag on each resolution attempt

The module-level auxiliary_is_nous was set to True by _try_nous() and
never reset. In long-running gateway processes, once Nous was resolved
as auxiliary provider, the flag stayed True forever — even if
subsequent resolutions chose a different provider (e.g. OpenRouter).
This caused Nous product tags to be sent to non-Nous providers.

Reset the flag at the start of _resolve_auto() so only the winning
provider's flag persists.

agent/auxiliary_client.py

@@ -706,6 +706,8 @@ def _resolve_forced_provider(forced: str) -> Tuple[Optional[OpenAI], Optional[st
 
 def _resolve_auto() -> Tuple[Optional[OpenAI], Optional[str]]:
     """Full auto-detection chain: OpenRouter → Nous → custom → Codex → API-key → None."""
+    global auxiliary_is_nous
+    auxiliary_is_nous = False  # Reset — _try_nous() will set True if it wins
     for try_fn in (_try_openrouter, _try_nous, _try_custom_endpoint,
                    _try_codex, _resolve_api_key_provider):
         client, model = try_fn()