ci: add releaseo release workflow

[peppescg]

Summary

Add automated release workflow using releaseo, following the same pattern as toolhive-registry-server.

Changes

This PR adds two new GitHub workflows:

1. create-release-pr.yml

• Trigger: Manual (workflow_dispatch)
• Purpose: Creates a release PR with automated version bumping
• Updates:
  • VERSION file (single source of truth)
  • helm/Chart.yaml (version and appVersion)
  • helm/values.yaml (image.tag with v prefix)

2. create-release-tag.yml

• Trigger: Push to main when VERSION file changes
• Purpose: Creates git tag and GitHub Release after release PR is merged
• Safety checks:
  • Validates semver format
  • Verifies commit message matches release pattern
  • Prevents accidental tags from manual VERSION edits

Release Flow

Step	Action	Workflow
1	Go to Actions → "Create Release PR" → Select bump type (patch/minor/major)	Manual
2	Releaseo bumps VERSION, Chart.yaml, values.yaml and creates PR	create-release-pr.yml
3	Review and merge the release PR to main	Manual
4	Tag vX.Y.Z and GitHub Release are created automatically	create-release-tag.yml
5	Docker image is built and pushed to GHCR	docker-publish.yml
6	Helm chart is packaged and published to GHCR	releaser-helm-chart.yml

[Copilot]

Pull request overview

Adds an automated release process using releaseo, creating a manual workflow to open a release PR and an automatic workflow to tag and publish a GitHub Release when VERSION changes on main.

Changes:

• Add a manual workflow_dispatch workflow to bump versions and open a release PR via stacklok/releaseo.
• Add a push-triggered workflow to validate VERSION, verify the release commit pattern, and create/push a vX.Y.Z tag and GitHub Release.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
.github/workflows/create-release-pr.yml	Adds a manual workflow to create a release PR and bump version fields (Chart/appVersion/image.tag).
.github/workflows/create-release-tag.yml	Adds an automated workflow to validate release commits on main and create a release tag + GitHub Release.