This PR makes it so we use more types and constants from the `zed_llm_client` crate to avoid duplicating information. Also updates the current usage endpoint to use limits derived from the `Plan`. Release Notes: - N/A
This PR makes it so we use more types and constants from the `zed_llm_client` crate to avoid duplicating information. Also updates the current usage endpoint to use limits derived from the `Plan`. Release Notes: - N/A