refactor(cli): remove unused warning helper (#39962)

Co-authored-by: Kit Langton <kit.langton@gmail.com>

packages/cli/src/run/run.ts

@@ -235,10 +235,6 @@ async function renderToolError(part: SessionMessageAssistantTool, directory: str
   UI.println(UI.Style.TEXT_NORMAL + "✗", UI.Style.TEXT_NORMAL + `${info.title} failed`)
 }
 
-function warning(message: string) {
-  UI.println(UI.Style.TEXT_WARNING_BOLD + "!", UI.Style.TEXT_NORMAL, message)
-}
-
 function errorMessage(error: unknown) {
   if (error instanceof Error) return error.message
   if (typeof error === "object" && error !== null && "message" in error && typeof error.message === "string")