Add GitHub Actions checks, test script, and skip-main flag to uki-setup

[GlitchSlayed]

Motivation

• Add automated CI to lint and validate uki-setup.sh and its generated artifacts in a Fedora container on push and PRs.
• Allow test harnesses to source the script without running the main workflow by providing a skip-main switch.
• Make the post-install summary robust against missing glob matches when listing UKI files.

Description

• Add .github/workflows/checks.yml which runs a Fedora container, installs shell tooling, and executes bash -n, shellcheck, and the project check script.
• Add tests/test_uki_setup.sh which sets UKI_SETUP_SKIP_MAIN=1, sources uki-setup.sh, invokes phase_write_build_script and phase_write_plugin, and validates template substitution and generated file contents.
• Document the CI checks and local reproduction commands in README.md.
• Modify uki-setup.sh to replace ls -lh "${EFI_DIR}"*.efi with find "${EFI_DIR}" -maxdepth 1 -type f -name "*.efi" -exec ls -lh {} + to avoid shell glob issues.
• Guard the script main execution with if [[ "${UKI_SETUP_SKIP_MAIN:-0}" -ne 1 ]]; then ... fi so tests can source the file safely.

Testing

• Run bash -n uki-setup.sh tests/test_uki_setup.sh to verify Bash syntax, which succeeded.
• Run shellcheck -P . uki-setup.sh tests/test_uki_setup.sh to lint the scripts, which succeeded.
• Run the project check bash tests/test_uki_setup.sh to validate generated artifacts and template substitution, which succeeded.

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Codex Task

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Handle skip-main flag without arithmetic evaluation

The new UKI_SETUP_SKIP_MAIN guard uses -ne, which triggers arithmetic evaluation under set -u; if a caller sets UKI_SETUP_SKIP_MAIN to a common string boolean like true/false, Bash treats that token as a variable name and exits with an unbound-variable error before any phase runs. This makes the script unexpectedly fail in automation environments that pass string-valued env flags instead of numeric 0/1.

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