[Question] SELECT ... INTO OUTFILE returns 'Unsupport select statement' on Cloud (works locally)

## Summary
`SELECT ... INTO OUTFILE` returns "Unsupport select statement" on MatrixOne Cloud (both `stage://` and local paths). It works on a local self-hosted instance. Filing to confirm whether this is an intentional Cloud restriction and to document it.

## Environment
- **Reported on:** MatrixOne Cloud free tier, `8.0.30-MatrixOne-v3.0.11`
- **Retested on:** local Docker `matrixorigin/matrixone` **main branch** build, Git commit `0bfda60` (built 2026-05-30), version string `8.0.30-MatrixOne-v`

## Test case
```sql
SELECT * FROM products INTO OUTFILE 'stage://mystage/p.csv'; -- Cloud: fails
SELECT * FROM products INTO OUTFILE '/tmp/p.csv'; -- Cloud: fails; local: works
```

## Actual result (Cloud)
```
ERROR 1149 (HY000): SQL syntax error: Unsupport select statement
```

## Version status
- v3.0.11 (Cloud): reproduces (disabled)
- main / 4.0-dev (local): works — Cloud-specific. Please confirm if intended and document the supported export path on Cloud.