feat(llm): standardize config key naming to use hyphens

Changed the config key 'llm-server-n_ctx_size' to 'llm-server-n-ctx-size' in local.rs to maintain consistent hyphen-separated naming convention across configuration parameters. This improves code readability and aligns with existing naming patterns.

src/llm/local.rs

@@ -230,7 +230,7 @@ pub async fn start_llm_server(
         .unwrap_or("50".to_string());
 
         let n_ctx_size = config_manager
-        .get_config(&default_bot_id, "llm-server-n_ctx_size", None)
+        .get_config(&default_bot_id, "llm-server-n-ctx-size", None)
         .unwrap_or("4096".to_string());