Replace external Actions with native runner/buildx capabilities in repo workflows

[Copilot]

This change removes third-party workflow dependencies that are no longer needed and shifts artifact/download and Docker caching to native GitHub tooling. It also tightens workflow robustness around artifact tag extraction.

• Action dependency reduction

  • Removed unfor19/install-aws-cli-action from sync.yml and repos.yml; workflows now rely on the AWS CLI preinstalled on ubuntu-latest.
  • Replaced dawidd6/action-download-artifact with gh run download in both repos.yml jobs.

• Native Buildx cache enablement

  • Added GitHub Actions cache backend to docker/build-push-action in image.yml using type=gha with mode=max.

• Permissions + artifact handling hardening

  • Added explicit actions: read permission (alongside contents: write) for jobs that download artifacts via gh.
  • Updated TAG discovery logic to fail fast when the artifact is missing or empty, preventing silent downstream failures.

- name: Build and push
  uses: docker/build-push-action@v7
  with:
    context: build
    file: build/fpm.Dockerfile
    push: true
    tags: ghcr.io/${{ github.repository_owner }}/fpm:latest
    cache-from: type=gha
    cache-to: type=gha,mode=max

[Copilot]

Pull request overview

This PR modernizes the repository’s GitHub Actions workflows by removing third-party actions and relying on native runner tooling (GitHub CLI, preinstalled AWS CLI) plus Buildx’s native GHA cache backend, while hardening artifact TAG extraction to fail fast.

Changes:

• Replaced third-party artifact download action with gh run download and added job permissions needed for artifact access.
• Removed explicit AWS CLI install steps and relied on runner-provided AWS CLI.
• Enabled Buildx caching via the GitHub Actions cache backend (type=gha) for Docker image builds.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
.github/workflows/sync.yml	Removes AWS CLI install action and relies on runner-provided AWS CLI for R2 sync.
.github/workflows/repos.yml	Switches artifact downloads to gh run download, adds permissions, and hardens TAG discovery.
.github/workflows/image.yml	Enables Buildx cache-from/cache-to using type=gha for faster image builds.

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