LLM adapter backed by the optional ReqLLM dependency.
Translates Mnemosyne.LLM calls to ReqLLM's generate_text/3 and
generate_object/4 APIs. Structured output is parsed through the supplied
Zoi schema to preserve the key types expected by Mnemosyne's prompts.
Requires a :model option in ReqLLM's "provider:model" format. The optional
:step is used for telemetry; remaining options are forwarded to ReqLLM.
Usage and costs are preserved, with cache token aliases added for Mnemosyne.