[codex] benchmark definition simplification refactor

[MRiabov]

What changed

This branch captures the benchmark-definition simplification work that landed over the last 16 hours and separates it from the pre-change main history.

The branch includes:

• the benchmark contract refactor across controller, worker, shared schema, templates, seed data, and integration tests
• the spec plan in specs/benchmark-definition-simplification-refactor.md
• the related config/skills_repo.lock.json update

Why

The goal is to move benchmark scenario/pricing data into benchmark_definition.yaml and keep the benchmark CAD plan in benchmark_assembly_definition.yaml, instead of coercing benchmark handoffs through the engineer-style AssemblyDefinition shape.

Impact

• main now points back to the pre-refactor baseline
• benchmark-definition-dedupe-refactor-start carries the high-churn benchmark schema and workflow changes
• future benchmark planner/reviewer work can treat the spec document as the source of truth for the split contract

Validation

• Verified the branch split locally with git log and git ls-remote
• No integration test run was performed as part of this PR creation step

[github-actions]

🤖 Hi @MRiabov, I've received your request, and I'm working on it now! You can track my progress in the logs for more details.

[MRiabov]

@codex can you complete? See the new file in latest commits in specs/

[chatgpt-codex-connector]

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