fix: add explicit permissions to GitHub Actions workflow jobs

[Copilot]

GitHub Actions jobs in three workflows were running without explicit permissions blocks, leaving them subject to potentially over-broad default GITHUB_TOKEN permissions (read-write on older repos/orgs).

Changes

• .github/workflows/docker-image.yml — added permissions: contents: read to both the build and merge jobs (alerts Lastprofil #1, Battery is force charged after being below minimum #50)
• .github/workflows/pylint.yml — added permissions: contents: read to the lint job (alert Problem beim Start #2)
• .github/workflows/pytest.yml — added permissions: contents: read to the test job (alert Adding new variables and additional flexibility for config (FC Solar, Fronius) #5)

All affected jobs only need to read repo contents; Docker Hub pushes use external secrets and don't require any GITHUB_TOKEN write scope.

  build:
    runs-on: ubuntu-latest
    permissions:
      contents: read  # added — was missing entirely

[Copilot]

Pull request overview

This PR hardens the repository’s GitHub Actions security posture by explicitly scoping GITHUB_TOKEN permissions on jobs that only need to read repository contents, avoiding reliance on potentially broader default permissions.

Changes:

• Added permissions: contents: read to the test job in pytest.yml.
• Added permissions: contents: read to the lint job in pylint.yml.
• Added permissions: contents: read to both build and merge jobs in docker-image.yml.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
.github/workflows/docker-image.yml	Restricts token permissions for Docker build/merge jobs to read-only repo access.
.github/workflows/pylint.yml	Restricts token permissions for the lint job to read-only repo access.
.github/workflows/pytest.yml	Restricts token permissions for the test job to read-only repo access.