Switch PR/push CI, Playwright, image publish validation, and manual
workflows from GitHub-hosted labels to the repo's online self-hosted
runners (evo Linux, air/mini macOS). release-desktop keeps
windows-2022 only when Windows signing credentials are configured;
there is no self-hosted Windows runner.
Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: cynarAI <cynarAI@users.noreply.github.com>