#275 CONV-314: Add OpenAPI validation test

Summary

• Adds openApiSpec() helper to tests/Pest.php using symfony/yaml
• Adds validation test that parses the YAML and checks required root keys
• Adds symfony/yaml as dev dependency

Test plan

• composer test passes (603 tests)

🤖 Generated with Claude Code

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Summary by cubic

Adds a validation test for our OpenAPI YAML to catch structural regressions and ensure required root keys are present. Fulfills CONV-314 by adding a parsing helper and the symfony/yaml dev dependency.

• New Features

  • Added openApiSpec() test helper to parse docs/api/openapi.yaml.
  • New test verifies presence of openapi, info, paths, and components.
  • Minor quote fix in docs/api/openapi.yaml to ensure valid YAML.

• Dependencies

  • Added dev dependency symfony/yaml@^7.4.