chore: Add scheduled workflow for nightly Docker image releases

[Copilot]

Automates daily builds of nightly2 and nightly2-rootless Docker images to Docker Hub and GitHub Container Registry.

Changes

• New workflow: .github/workflows/nightly-release.yml
  • Scheduled daily at 02:00 UTC via cron
  • Sets up Docker Buildx with QEMU for multi-platform builds (amd64, arm64, armv7)
  • Authenticates to both registries using secrets
  • Executes npm run release-nightly to build and push images
  • Includes manual trigger option via workflow_dispatch

Required Secrets

Configure in repository settings:

• DOCKERHUB_USERNAME / DOCKERHUB_TOKEN - Docker Hub credentials
• GHCR_USERNAME / GHCR_TOKEN - GitHub Container Registry credentials (token needs write:packages scope)

Original prompt

Create a workflow, run npm run release-nightly at 2:00 am everyday, the script will build and push the nightly2 docker image to Docker Hub and GitHub Registry. I probably need to provide auth token in secret. Please let me know the secret name that I have to set.

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[Copilot]

Pull request overview

This PR adds automated nightly Docker image builds for Uptime Kuma, scheduled to run daily at 02:00 UTC. The workflow builds and publishes nightly2 and nightly2-rootless images to Docker Hub and GitHub Container Registry.

Changes:

• Adds .github/workflows/nightly-release.yml with scheduled and manual triggers
• Configures multi-platform Docker builds (amd64, arm64, armv7) using QEMU and Buildx
• Sets up authentication for Docker Hub and GitHub Container Registry

[Copilot]

For GitHub Container Registry authentication, you can use the built-in GITHUB_TOKEN instead of requiring separate GHCR_USERNAME and GHCR_TOKEN secrets. This is the recommended approach for GitHub Actions workflows and simplifies configuration. Change the username to use github.actor and password to use secrets.GITHUB_TOKEN, which is automatically available in all GitHub Actions workflows with the packages: write permission already set.

Suggested change

	username: ${{ secrets.GHCR_USERNAME }}
	password: ${{ secrets.GHCR_TOKEN }}
	username: ${{ github.actor }}
	password: ${{ secrets.GITHUB_TOKEN }}

[louislam]

Ah... no permission, man, you are wrong.