#290 CONV-329: Add API documentation final smoke tests

Summary

• Adds smoke test asserting all 9 Phase 19 API endpoints are documented
• Adds smoke test asserting all 7 required schemas exist
• Adds smoke test confirming /docs/api is publicly accessible without auth
• Fixes lint issues in test files

Test plan

• composer test passes (620 tests)
• composer lint passes
• npm run build passes

🤖 Generated with Claude Code

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Summary by cubic

Adds final smoke tests for API docs (CONV-329): verify all Phase 19 endpoints and required schemas exist in the OpenAPI spec, and confirm /docs/api is publicly accessible without auth. Also cleans up test lint issues and imports Symfony\Component\Yaml\Yaml for parsing the spec.