feat: add create-deployment input for GitHub Deployment tracking

[0x46616c6b]

Type of Change

• Enhancement / new feature

Description

Add an opt-in create-deployment boolean input that creates GitHub Deployments on the source repository and writes tracking annotations to the Application CR in the mops overlay.

This enables the flux-deployment-reporter to directly identify and update the correct GitHub Deployment without image-to-repo mapping or tag parsing.

New inputs:

• create-deployment (boolean, default false) — no breaking change
• github-token — required when create-deployment is true, needs deployments: write permission

New output:

• deployment-id — JSON map of environment to GitHub Deployment ID (e.g. {"prod-de1": "12345", "prod-us1": "67890"})

Behavior when create-deployment is true:

• Creates a GitHub Deployment per target file/cluster via the GitHub API
• Sets initial deployment status to in_progress
• Derives environment name from mops file path (kubernetes/namespaces/<svc>/<env>/<cluster>/... → <env>-<cluster>)
• Writes three annotations on each Application CR:
  • deploy.staffbase.com/repo — source repository
  • deploy.staffbase.com/sha — full commit SHA
  • deploy.staffbase.com/deployment-id — GitHub Deployment ID
• Soft-fails on API errors (warning emitted, image update proceeds)

Also updates README examples to use actions/checkout@v6, ubuntu-24.04, and [email protected].

Closes CI-1201

Checklist

• Write tests
• Make sure all tests pass
• Update documentation
• Review the Contributing Guideline and sign CLA
• Reference relevant issue(s) and close them after merging

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_{The changes and the PR were generated by Claude.}