Refactor CLI recipe dry-run helpers

[chubes4]

Summary

• Extract recipe dry-run planning/output helpers from the CLI entrypoint into packages/cli/src/recipe-dry-run.ts.
• Keep index.ts responsible for command routing and shared recipe execution while reusing dry-run helpers for site-seed metadata and plugin-runtime step indexes.
• Preserve existing recipe dry-run output shape and CLI behavior.

Tests

• npm run build
• npm run recipe-dry-run-smoke
• npm run recipe-workflow-phases-smoke
• npm run discovery-command-smoke
• npm run recipe-site-seed-smoke
• npm run recipe-staged-files-smoke

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (openai/gpt-5.5)
• Used for: Drafted the focused extraction and ran build/smoke verification; Chris remains responsible for review and merge.