Introduces a new `LlmBackend` struct to centralize LLM configuration.
This change refactors the `call_llm` function in both `run_full_case.rs`
and `run_llm_only.rs` to accept an `LlmBackend` instance instead of
individual settings.
The `doctate_server::analyze::backend` module is now used to obtain the
default backend, simplifying configuration and improving consistency.
The `clone_backend_with_system_prompt` helper function is introduced to
allow temporary modification of LLM backends for experimentation without
altering the production catalog.
This change improves code organization and makes it easier to manage LLM
configurations across different parts of the application.
Brummel
012e6732b3