pub fn default_backend() -> SharedBackendExpand description
Factory that builds the default backend for the current build configuration.
v1.0.89 (GAP-META-006): uses detect_available_backend() to resolve
the LLM CLI at runtime instead of hardcoding codex. The user’s
--llm-backend flag (propagated via env var) is honoured by the
factory infrastructure in llm_backend.rs.