Mark every GitHub release on Grafana dashboards and Slack

I want a deterministic code workflow (trigger plus two known operations, not an agent) that runs whenever a new release is published in GitHub, drops a deployment marker on our Grafana dashboards, and posts a heads-up in Slack.

Trigger: a GitHub outgoing webhook on the release event. The workflow should only fire when action equals "published" AND the release is not a draft AND not a prerelease. Skip the run otherwise.

Step 1: Call Grafana's Create Annotation operation. Make it a global, point-in-time annotation, so do not set a dashboard ID or panel ID. Tag it with "deployment" and the repo full name (for example "deployment" and "acme/api"). Set the annotation time to the release's published_at timestamp converted to epoch milliseconds, so the marker lands at the exact deploy moment even if the workflow runs a few seconds late. The annotation text should include the release name, the tag name, and a short excerpt of the release body.

Step 2: Call Slack Bot's Send a Message operation to post in a channel I choose (default to #deploys). The message should include: the release name and tag, a link to the GitHub release (the html_url from the payload), and a link back to our Grafana home (or a specific service dashboard URL I can configure) so on-call can scroll the graph and visually correlate any post-deploy regression. Use the Slack Bot integration so the post comes from a shared bot identity, not a single user.

Please ask me for: (1) the GitHub repo or repos to listen to, (2) the Slack channel to post in, and (3) the Grafana dashboard URL to link to in the Slack message (default to the Grafana home page if I don't have a preference).