v0.9.81: GitHub Action + config precedence fix

What's Changed

• feat: the GPC GitHub Action is live on the Marketplace. Publish to Google Play from GitHub Actions in one step, with a built-in preflight compliance gate. Drop-in migration from r0adkll/upload-google-play: the same inputs work, so switching is a one-line change.
• fix: GPC_SERVICE_ACCOUNT / GPC_APP environment variables and the --service-account / --app flags now override an active config profile. Previously the profile could win and target the wrong app or account.
• docs: the CI/CD guide now features the action as the quickest path.

Full Changelog: v0.9.80...v0.9.81