PowerShell editing round-tripped the U+2192 arrows through cp1252 in
06_reference_app/03_pipelines_and_worker.md; restored them and regenerated
the wiki HTML + MCP module.
- four pages walking the vet sample: overview, domain & API, pipelines &
worker, spec-driven client admin
- mkdocs nav section, index + start-an-app cross links
- bundle now exposes the walkthrough as wiki_reference_app_* modules