Campaign content and listmonk credentials now live in separate
per-domain repos that install this tool at a pinned version, so a
client with access to one domain's content repo has no path to
another domain's secrets. Renames the module to the actual Gitea
host path so `go install` works without vanity-import redirects,
drops the four workflows that assumed campaigns/ content lived here,
adds real go-test CI, and rewrites the README for the tool's new
audience.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>