[FEAT] Dockerfile

[bbengfort]

Scope of changes

Implements container and container build process for the service.

Estimated PR Size:

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Acceptance criteria

This PR will be merged without review.

Author checklist

• I have manually tested the change and/or added automation in the form of unit tests or integration tests
• I have updated the dependencies list
• I have added new test fixtures as needed to support added tests
• I have added or updated the documentation
• I have run go generate to update generated code

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Note

Medium Risk
Introduces new CI/CD automation that builds and pushes images using registry credentials and new build args; failures or misconfiguration could block releases or publish incorrect tags.

Overview
Adds first-class containerization for the uptime service via a new multi-stage Dockerfile that builds a static binary and injects GitVersion/BuildDate via -ldflags.

Introduces a new .github/workflows/containers.yaml workflow to build multi-arch images on pushes/tags, generate semver/SHA tags, and push to DockerHub and GCR (pushes disabled on PRs) using repository secrets.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Unused tag output variable in workflow step

Low Severity

The tag output computed in the Set Environment step is never referenced anywhere in the workflow. Only revision and build_date are consumed (via steps.vars.outputs.revision and steps.vars.outputs.build_date). The tag output is dead code that adds confusion about whether something downstream was supposed to use it.