fix: use safe tar extraction in env pull to prevent path traversal

[JannikSt]

Replace unsafe tar.extractall() in env pull with the existing _safe_tar_extract helper that validates archive members against path traversal, symlink, and absolute path attacks.

• Use _safe_tar_extract instead of raw extractall in the pull command
• Catch ValueError from validation alongside TarError

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Note

Medium Risk
Touches archive extraction in the CLI download path, which is security-sensitive; behavior changes are small but could cause pulls to fail if archives contain previously-accepted unsafe entries.

Overview
Security hardening for prime env pull. Replaces direct tar.extractall() with _safe_tar_extract() so pulled environment archives are validated against path traversal, absolute paths, and link entries before extraction.

Extraction now also treats validation failures (ValueError) as user-facing extraction errors alongside tarfile.TarError.

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