Add YAML output format support

[andrewshadura]

YAML is useful as it’s slightly more compact and readable than JSON.

This requires the serde_yaml dependency.

Fixes: #40

[sjoerdsimons]

serde_yaml is unmaintined so might not be the best optoin to introduce at this point

[Copilot]

Pull request overview

Adds YAML as an additional structured output format for aptlyctl list-style commands, enabling more compact/readable exports alongside existing JSON support.

Changes:

• Extend OutputFormat with a Yaml variant and wire it into snapshot/repo/publish listing outputs.
• Add YAML support for repo packages list detailed results output.
• Introduce the serde_yaml dependency (and update Cargo.lock accordingly).

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
aptlyctl/src/main.rs	Adds Yaml to the CLI output format enum.
aptlyctl/src/snapshot.rs	Enables YAML output for snapshot list.
aptlyctl/src/repo.rs	Enables YAML output for repo list and repo packages list.
aptlyctl/src/publish.rs	Enables YAML output for publish list.
aptlyctl/Cargo.toml	Adds serde_yaml dependency.
Cargo.lock	Locks serde_yaml and its transitive dependencies.

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[Copilot]

The YAML output branch doesn’t emit a trailing newline, but the JSON branch does (via println!()). For consistent CLI UX (especially when piping / printing to a terminal), consider adding a newline after writing YAML as well.

Suggested change

	}
	println!();

[Copilot]

The YAML output branch writes the document but doesn’t add a trailing newline, whereas the JSON branch prints one. Consider adding a newline after YAML output to keep list output formatting consistent and avoid prompts appearing on the same line.

Suggested change

	serde_yaml::to_writer(&mut stdout(), &publishes)?;
	serde_yaml::to_writer(&mut stdout(), &publishes)?;
	println!();

[Copilot]

The Json and Yaml branches both re-run the same detailed() query and the same empty-check, which is duplicated logic. Consider fetching results once and then serializing based on the selected structured output format to reduce duplication and make it harder for the two branches to drift over time.

[Copilot]

Adding serde_yaml = "0.9" currently resolves to serde_yaml 0.9.34+deprecated (see Cargo.lock) and brings in unsafe-libyaml (FFI/unsafe code). If YAML output is required, consider switching to a maintained alternative (e.g., serde_yaml_ng) or otherwise pinning/justifying the choice, since deprecated + FFI dependencies can have long-term maintenance and security implications.

Suggested change

	serde_yaml = "0.9"
	serde_yaml_ng = "0.10"

[Copilot]

The YAML output branch doesn’t print a trailing newline, while the JSON branch prints one. This can lead to the next shell prompt appearing on the same line and is inconsistent with the JSON output for list. Consider printing a newline after writing YAML as well (or otherwise ensuring output ends with \n).

Suggested change

	serde_yaml::to_writer(&mut stdout(), &snapshots)?;
	serde_yaml::to_writer(&mut stdout(), &snapshots)?;
	println!();