Issue: auxiliary tasks don't respect user's provider-level base_url (falls back to hardcoded PROVIDER_REGISTRY)

Summary

When a user configures a custom base_url for a provider (e.g., xiaomi with token-plan-sgp.xiaomimimo.com), auxiliary tasks (session_search, compression, title_generation, flush_memories, approval) ignore the user's providers.<name>.base_url and instead use the hardcoded inference_base_url from PROVIDER_REGISTRY in hermes_cli/auth.py. This causes silent failures — auxiliary tasks timeout/401 and fall back to other providers, creating cascading issues (gateway idle timeouts, broken session_search).

Root Cause

auxiliary_client.py → _resolve_task_provider_model() reads auxiliary.<task>.provider but not base_url. When the task config only has provider: xiaomi, it returns with base_url=None, and later _resolve_api_key_provider() uses pconfig.inference_base_url — the hardcoded default.

Workaround (current)

Users must explicitly set base_url and api_key in EACH auxiliary.<task> section, requiring credential duplication across 5+ auxiliary tasks.

Desired Behavior

auxiliary.<task>.provider should inherit base_url and api_key from providers.<name> when not explicitly overridden. Resolution chain:

1. auxiliary.<task>.base_url / api_key (explicit override)
2. providers.<task_provider>.base_url / api_key (inherit from provider)
3. Hardcoded PROVIDER_REGISTRY default

Affected Code

• agent/auxiliary_client.py: _resolve_task_provider_model() — returns None for base_url when only provider is set
• agent/auxiliary_client.py: _resolve_api_key_provider() — uses pconfig.inference_base_url unconditionally

Environment

• Hermes v0.11.0
• Provider: xiaomi (MiMo) with non-standard base_url