chore(ci): add automatic github release

[nevermarine]

Description

Add automatic GitHub release handling to the Deploy Prod workflow and extend Loop notifications with GitHub release status.

Why do we need it, and what problem does it solve?

Deploy Prod already publishes module versions to release channels, but GitHub releases are still created separately. This change lets the workflow automatically prepare a GitHub release from the generated changelog PR for the same version.

For testing, the release creation step is temporarily switched to dry-run mode and Loop notifications are sent to the test webhook channel. This makes it possible to validate PR lookup, release notes generation, and notification formatting without creating a real GitHub release or posting to the production Loop channel.

What is the expected result?

1. Run Deploy Prod with release_to_github=true for a tag that has exactly one merged changelog PR with milestone equal to the tag.
2. Verify the workflow checks whether a GitHub release for the tag already exists.
3. If the release does not exist, verify the workflow finds the changelog PR and prints the exact gh release create command it would execute.
4. Verify the workflow logs the generated release notes content.
5. Verify the Loop notification is sent to LOOP_TEST_CHANNEL and includes a separate GitHub release section.
6. Verify check_only=true or release_to_github=false skips the GitHub release step.

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: ci
type: feature
summary: "Deploy Prod workflow can prepare GitHub releases from changelog PRs and report release status to Loop."
impact_level: low