Reusable workflow renamed to publish.yaml

The reusable workflow file path becomes part of the public API once tagged — so timing matters. Before consumers could pin to publish.yaml, the file has been renamed to better reflect what it actually does. "Analyze" was only the first step; the workflow runs analysis, builds, and deploys to Pages. "Publish" captures the full lifecycle.

Three files were updated: the workflow itself, the caller in self-deploy.yml, and the install snippet in README.md. The internal name: field was also updated to "Gitpulse Publish" to match.