Same class as the resolve_nous_access_token memo: three more process-wide
memos carried a credential resolved under one profile's HERMES_HOME override
into another profile's turn for their TTL.
- hermes_cli/nous_billing.py::_token_cache (30s (token, base) memo for the
charge poll loop) was a single unkeyed slot -> dict keyed by
hermes_home_key(); invalidate_cached_token() clears the dict.
- agent/moa_loop.py::_runtime_cache carried api_key/base_url/api_mode keyed
only (provider, model) for 5 min -> (hermes_home_key(), provider, model).
- agent/auxiliary_client.py::_client_cache_key had no profile component, so
callers that omit api_key (pool / Nous auth.json paths) could be handed a
client built with another profile's bearer -> hermes_home_key() leads the key.
WHY hermes_home_key(): it reads the per-turn HERMES_HOME override the
multiplex gateway sets (falling back to the env var), and it is
symlink-stable, so the memo key is exactly the credential home the
resolution itself read from. Profiles stay independent islands; the
default-profile process env never leaks into a secondary's turn.
Tests: one invariant per site, proven red on origin/main.
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