chore(deps): update docker/login-action action to v4

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
docker/login-action	action	major	v3 → v4

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Release Notes

docker/login-action (docker/login-action)

v4

Compare Source

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Configuration

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[claude]

This is a straightforward dependency update from Renovate bumping docker/login-action from v3 to v4 in the Docker build/push workflow.

Assessment: Safe to merge.

• The change is a single-line major version bump of a well-maintained official Docker GitHub Action
• docker/login-action@v4 is the current stable release maintained by Docker
• No logic changes — only the action version reference is updated
• The action is used for authenticating to GitHub Container Registry (ghcr.io), which is standard and low-risk
• Renovate-managed dependency updates like this are routine maintenance

No concerns with code quality, security, or correctness. This keeps the CI pipeline on a supported action version.