[locus313]

Description

Improves how github-enterprise-billing-report reads and lays out its output:

• Wraps the report body in <main> so a BRAND_CSS stylesheet can lay out a full-width header and footer.
• Names Actions runner SKUs from their code (for example actions_linux_4_core becomes "Linux 4-core runner minutes"), so new runner sizes get a readable name without a code change.
• Names the Copilot premium request SKU and aligns "Copilot AI Credits" with "Copilot AI usage".
• Adds thousands separators to money amounts and billed quantities ($4,753.00, 1,098 minutes). The CSV keeps raw numbers.
• Leaves usage with a repository but no organization out of the repository ranking. It previously showed as /my-repo next to my-org/my-repo; the amount is still counted in the Enterprise account table.
• Explains in the Enterprise account section that charges returned without organization detail can shrink over time.

Changes

• Modified: reporting/github-enterprise-billing-report/github-enterprise-billing-report.sh
• Other: docs/script-behaviors.md

How to test

export GITHUB_TOKEN=ghp_REDACTED
export GITHUB_ENTERPRISE=my-enterprise
MONTHS=12 ./reporting/github-enterprise-billing-report/github-enterprise-billing-report.sh

Open the HTML report and check that amounts of $1,000 or more have separators, Actions SKUs have readable names, each repository appears once in the top repositories table, and BRAND_CSS styling applies to the header and footer. bats tests/ and shellcheck pass.

Checklist

• set -euo pipefail is the first executable line after the # === header
• Script sources lib/github-common.sh via SCRIPT_DIR
• All required env vars validated with require_env_var
• Token validated with validate_github_token
• User-supplied slugs validated with validate_slug
• README.md and docs/script-behaviors.md updated where behavior changed
• Script header comment matches README documentation
• shellcheck passes (shellcheck --severity=warning --exclude=SC2034,SC1091 --shell=bash <script>)