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.test.ts

@@ -144,7 +144,7 @@ describe('runNonInteractive', () => {
       }),
       getExperimentalZedIntegration: vi.fn().mockReturnValue(false),
       isInteractive: vi.fn().mockReturnValue(false),
-      isCronDisabled: vi.fn().mockReturnValue(true),
+      isCronEnabled: vi.fn().mockReturnValue(false),
       getCronScheduler: vi.fn().mockReturnValue(null),
     } as unknown as Config;