fix: use 2-space indentation in generated compose.yaml

[Copilot]

Description

Switch the generate command from using yaml.Marshal (which produces 4-space indented output) to compose.WriteYAML with SetIndent(2), so that the generated compose.yaml uses standard 2-space indentation. Update all test expected outputs to match the new 2-space format.

What does this PR do?

The generate command previously used yaml.Marshal to serialise the Compose project, which produced 4-space indented YAML. This PR replaces that call with compose.WriteYAML (backed by SetIndent(2)), aligning the generated compose.yaml output with the conventional 2-space indentation used across the Compose ecosystem. All affected golden-string expectations in generate_test.go, generate_examples_test.go, and init_test.go are updated accordingly.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• New chore (expected functionality to be implemented)

Checklist:

• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• I've signed off with an email address that matches the commit author.

[github-actions]

Overview

Image reference	score-compose:latest	score-compose:latest
- digest	4ceb43162d1e	bd6d13e996a2
- tag	latest	latest
- provenance	aa92490	021ea05
- vulnerabilities
- platform	linux/amd64	linux/amd64
- size	6.2 MB	6.2 MB (+850 B)
- packages	54	54

Policies (0 improved, 0 worsened)

Policy Name	score-compose:latest	score-compose:latest	Change	Standing
Default non-root user	✅	✅		No Change
No AGPL v3 licenses	✅	✅		No Change
No fixable critical or high vulnerabilities	✅	✅		No Change
No high-profile vulnerabilities	✅	✅		No Change
No outdated base images	✅	✅		No Change
No unapproved base images	✅	✅		No Change
Supply chain attestations	✅	✅		No Change
Valid Docker Hardened Image (DHI) or DHI base image	⚠️ 2	⚠️ 2		No Change

Packages and Vulnerabilities (1 package changes and 0 vulnerability changes)

• ♾️ 1 packages changed
• 53 packages unchanged

Changes for packages of type golang (1 changes)

	Package	Version score-compose:latest	Version score-compose:latest
♾️	github.com/score-spec/score-compose	0.0.0-20260412232642-aa924900c12b+dirty	0.0.0-20260412233125-021ea05909f4+dirty

[mathieu-benoit]

I wanted a cleaner output file with 2-spaces indentation instead of 4-spaces, this LGTM

[mathieu-benoit]

@chris-stephenson, can I have a second pair of eyes by reviewing this one please? Thanks!

FYI, also trying to validate this approach in the other Score implementations:

• fix: use 2-space indentation in generated manifests YAML output score-implementation-sample#89
• fix: use 2-space indentation in generated YAML output score-k8s#286
• fix: use 2-space indentation in generated score.yaml score-helm#41
• fix: use 2-space indentation in generated score.yaml score-radius#66

[mathieu-benoit]

LGTM