refactor(measurement): decompose tooling by vocabulary

[binaryaaron]

Summary

• split W&B settings, metadata, policy, staging, publishing, reports, and workspaces into canonical modules
• split benchmark, sweep, and output-analysis responsibilities while preserving executable compatibility facades
• add import-linter contracts and characterization tests for module boundaries and dynamic loading

Stack

• base: refactor/module-vocabulary

Verification

• make check
• make test (1131 passed)
• PYTHONPATH=tools/measurement uv run --frozen lint-imports --config .importlinter (5 kept, 0 broken)
• Astnav index, cycle, coupling, and smartdiff gates
• final vocabulary legibility probe: 10/10