ability to override core system prompt (via .gemini/system.md) and specify core tools via coreTools setting (e.g. coreTools:["ls", "GrepTool", ...]) ; added tests, but did not update docs for now (#413)

packages/cli/src/config/settings.ts

@@ -21,6 +21,7 @@ export enum SettingScope {
 export interface Settings {
   theme?: string;
   sandbox?: boolean | string;
+  coreTools?: string[];
   toolDiscoveryCommand?: string;
   toolCallCommand?: string;
   mcpServerCommand?: string;