Rewrite the README around purpose, architecture, quickstart, and
status. Add contributing/security policies plus a docs index with
audience front matter across existing docs.
Update IA and status docs to reflect the landed M7d MPA conversion.
- docs/operator-ia.md: switch framing to implemented routes and add
/operator/persons/{personID} (lookup-only)
- openspec/changes/operator-mpa-conversion/tasks.md: mark verification
and documentation tasks as completed with notes on checks
- status/milestones.md: flip 7d to Done and summarize what landed
- status/operator-ux.md: add "7d Landed Decisions" section
- docs/design-system.md: small wording tweak about hx-boost navigations