[david-kariuki]

Summary

Aligns the existing shell sources with the formatting rules introduced by the CI workflow and cleans up an accidental duplicate test helper.

This fixes the Shell Formatting CI failure without changing bootstrap behaviour.

Changes

• quote associative-array keys in config/defaults.sh
• preserve hyphenated distro IDs such as:
  • opensuse-leap
  • opensuse-tumbleweed
• remove the duplicate lib/testlib.sh
• retain tests/testlib.sh as the canonical test harness
• normalize tracked shell files with shfmt
• add missing final newlines across shell sources

Validation

The following checks pass locally:

for shell_file in "${shell_files[@]}"; do
  bash -n "$shell_file"
done

[david-kariuki]

LGTM