Agent Skills: running-github-actions-efficiently

Cut GitHub Actions minutes and wall-clock time without losing coverage — the OS billing multiplier (macOS 10x / Windows 2x / Linux 1x), trigger hygiene that stops push+pull_request double-firing, concurrency that cancels superseded runs, dependency caching keyed on lockfiles, matrix discipline, and auditing scheduled crons that bill 24/7. Use when CI is burning included minutes, when runs feel slow, when setting up a new repo's workflows, or when reviewing an existing workflow for waste.