Add an architecture overview map in the profile

[4444J99]

Multiple participants struggled to understand how the various repositories (systems) interlock. A visual map is needed.

[4444J99]

Engagement disposition: distilled: profile/README.md. The org profile now includes an Architecture Overview section with a Mermaid flowchart mapping the wider organ system into the Logos repository map, plus a repository hand-off table showing .github, editorial-standards, reading-observatory, essay-pipeline, public-process, and analytics-engine.