unpack should create default sandbox-binary directory if not exists

[ronaldbradford]

Environment

• dbdeployer version: 2.3.0
• OS: macOS 25.4.0
• MySQL/database version: 8.4.8
• Flavor: MySQL
• Topology: single

Describe the bug
Documented instructions fail

Steps to reproduce

$ dbdeployer downloads get-by-version 8.4 --newest --minimal
Downloading mysql-8.4.8-macos15-arm64.tar.gz
File /tmp/mysql-8.4.8-macos15-arm64.tar.gz downloaded
Checksum matches
$ dbdeployer unpack mysql-8.4.8-*.tar.xz
directory '/Users/username/opt/mysql' not found
You should create it or provide an alternate base directory using --sandbox-binary

Expected behavior

$HOME/op/mysql is the default, you should pre-create if does not exist to simply usage.

Actual behavior

directory '/Users/username/opt/mysql' not found

[renecannao]

Thanks for the report. You're right that the directory isn't created by default — and looking at it, we don't want unpack to silently create paths on the user's behalf. But the error message was genuinely unhelpful: it told you a directory was missing without telling you what to do about it.

PR #114 keeps the safety check (no automatic mkdir) but rewrites the error to point at dbdeployer init --skip-all-downloads, which is the canonical command for setting up $SANDBOX_BINARY and $SANDBOX_HOME. It also includes a ready-to-copy mkdir -p <path> for users who'd rather create the directory manually. New output:

directory '/Users/username/opt/mysql' not found
Create it by running:
    dbdeployer init --skip-all-downloads
or manually with:
    mkdir -p /Users/username/opt/mysql
or provide an alternate base directory using --sandbox-binary

Closing this once the PR lands.