feat: add monthly optimization planner

[Pigbibi]

Summary

• add a normalized final AI review payload so upstream and downstream reviews share one machine-readable contract
• add a manual monthly optimization planner workflow plus artifact download, plan build, and issue upsert scripts
• cover the new planner and payload contract with unit tests and workflow config tests

Testing

• python3 -m unittest tests/test_build_ai_review_payload.py tests/test_download_ai_review_artifact.py tests/test_build_monthly_optimization_plan.py tests/test_post_monthly_optimization_issue.py tests/test_post_monthly_ai_review_comment.py tests/test_render_monthly_ai_review.py tests/test_run_openai_secondary_review.py tests/test_monthly_publish_workflow_config.py tests/test_monthly_optimization_planner_workflow_config.py
• uvx ruff check scripts tests
• ruby -e 'require "yaml"; Dir[".github/workflows/*.yml"].each { |f| YAML.load_file(f) }; puts "clr yaml ok"'
• local replay with gh run download using runs 23863391793 and 23863393303 to build optimization_plan.json / optimization_summary.md

Follow-up

• set CROSS_REPO_GITHUB_TOKEN in QuantStrategyLab/CryptoLeaderRotation before running monthly_optimization_planner.yml on GitHub Actions