fix(cli): preserve symlinks during sandbox upload

[mjamiv]

Summary

• build sandbox upload archives with symlink metadata instead of following links
• preserve symlink entries for whole-directory and git-style file-list uploads
• keep existing directory archive shape and file-list missing-entry behavior

Fixes #1425.

Testing

• cargo fmt --all -- --check
• git diff --check
• cargo test -p openshell-cli archive_preserves_symlink
• cargo test -p openshell-cli

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