feat(cron): make cron tools opt-in via experimental settings

Change cron/loop tools from opt-out to opt-in. Cron tools are now
disabled by default and can be enabled via:
- settings.json: { "experimental": { "cron": true } }
- Environment variable: QWEN_CODE_ENABLE_CRON=1

This ensures experimental features are explicitly enabled by users
who want to try them.

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

packages/cli/src/nonInteractiveCli.ts

@@ -372,7 +372,7 @@ export async function runNonInteractive(
           currentMessages = [{ role: 'user', parts: toolResponseParts }];
         } else {
           // No more tool calls — check if cron jobs are keeping us alive
-          const scheduler = config.isCronDisabled()
+          const scheduler = !config.isCronEnabled()
             ? null
             : config.getCronScheduler();
           if (scheduler && scheduler.size > 0) {