Compose formatter: preserve YAML anchors

[Copilot]

The Compose document formatter could push a YAML anchor onto its own line, breaking otherwise-valid compose fragments:

# before formatting
x-anchor: &anchor
  FOO: bar

# after formatting (broken)
x-anchor:
  &anchor
  FOO: bar

The formatter serializes via the yaml library's toString. The offending behavior originates in yaml and was fixed upstream in 2.2.2; the pinned yaml@2.9.0 in this repo already emits correct output for the reported example, merge-key (<<: *anchor) usage, sequence/scalar anchors, and the full docker-docs fragment pattern.

Changes

• Regression test (DocumentFormattingProvider.test.ts): added Should NOT break YAML anchors, formatting the issue's minimal example plus a merge-key alias and asserting the anchor stays inline / document is unchanged. Guards against reintroduction via a dependency downgrade or formatter option change.

No production code changes were required; the test documents and locks in the expected behavior.

• Fixes Compose formatter: YAML anchors broken by formatting #537

[Copilot]

Pull request overview

Adds coverage to ensure the Compose document formatter does not introduce anchor-breaking newlines, and introduces a Node entrypoint script for the compose language server package.

Changes:

• Add a regression test to ensure formatting doesn’t push YAML anchors onto a new line (Compose fragments remain valid).
• Add docker-compose-langserver executable wrapper script under packages/compose-language-service/bin/.

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 1 comment.

File	Description
packages/compose-language-service/src/test/providers/DocumentFormattingProvider.test.ts	Adds a formatter regression test for YAML anchor + merge-key (<<) scenarios.
packages/compose-language-service/bin/docker-compose-langserver	Adds the npm bin entrypoint wrapper that loads the built CJS server.

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