nightly-ad03b35f-ls298

CI Report:

https://ci-tests.linuxserver.io/linuxserver/beets/nightly-ad03b35f-ls298/index.html

LinuxServer Changes:

No changes

Remote Changes:

Fix integration tests (#6724)

This PR tightens the integration test workflow so CI runs the
dependency-heavy checks that are usually skipped in local environments.

What changed

• Install the system packages and Poetry extras needed by
  integration-only coverage, including ffmpeg/ffprobe,
  ImageMagick/Pillow-backed art resizing, chroma, docs, replaygain,
  reflink, lyrics, and related plugin dependencies.
• Run poe docs before poe test in the integration workflow and set
  LYRICS_UPDATED=1 so lyrics tests are included in CI.
• Centralize CI detection in beets.test.helper.RUNNING_IN_CI and reuse
  shared import/program checks across test collection and helpers.
• Keep dependency-heavy tests strict in the beetbox GitHub Actions
  environment, while skipping them locally when optional tools/modules are
  unavailable.
• Mark ffprobe-, artresizer-, chroma-, pandoc-, and completion-related
  cases with focused availability gates so local test runs fail less often
  for missing optional dependencies.
• Update docs link-check ignores and stale documentation URLs so poe check-docs-links is less noisy in CI.