Phase 2 backend. AssistantConfig is now live-updatable (RwLock) so the UI
toggle applies without a listener restart. New RPCs:
- mesh.assistant-status -> {enabled, model, trusted_only, default_model,
ollama_detected, models[]} (probes local Ollama :11434/api/tags)
- mesh.assistant-configure -> set enabled/model/trusted_only live + persist
MeshService::assistant_config / configure_assistant. Compiles clean.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>