docs: rewrite the README to describe the repository that exists

[Bryan Fawcett (bryanfawcett)]

The README described a 15-app super app with a Flutter shell, a live token
economy and a Next.js marketing site in web/. None of that is in the tree.

What is actually here, and what the README now says:

• mini-apps/ holds six Preact mini-apps - clips, connect, events, novels,
  pulse, weather - plus _template. Each is a single screen that renders a
  heading and one line of copy. The old list (Campfire, Mukoko News, Bytes,
  Circles, Nhimbe, BushTrade, Mukoko Lingo, Transport, Mukoko Wallet) named
  nine directories that do not exist.
• The repository description names six apps: ID, Clips, Pulse, Connect,
  Novels, Events. Five are the mini-apps above. ID is not a mini-app - it is
  services/id-api, and the identity product that ships is mukoko-dev/mukoko-auth
  at id.mukoko.com. Weather is a seventh mini-app the description omits. The
  README now says all three of those things.
• services/ holds six Hono workers plus _template. Every route handler returns
  {"message": "TODO: Implement ..."}. No worker declares a route or custom
  domain, so none of this is deployed. The README now leads with that rather
  than burying it.
• honey/ is a FastAPI service (package nuchi-honey 0.1.0) serving /health and
  / only; models/, routes/ and services/ are empty directories.
• web/ was stubbed in chore: stub web/ + web/studio with redirect notice (migrated to bundu-labs/marketing) #83; the marketing site moved to bundu-labs/marketing
  and was rebuilt in Astro 6. web/MIGRATED.md is now linked instead of the
  README claiming web/ is a Next.js 15 site you can develop in.
• The Flutter app/ directory was removed in Remove Flutter app scaffold and placeholder files #75. The README still documented
  it in the repo-structure tree and in the prerequisites table.
• packages/ names were wrong: the directories are design-system, bridge-sdk,
  api-client, types, eslint-config and tsconfig, publishing @mukoko/ui,
  @mukoko/bridge, @mukoko/api and @mukoko/types.

Dead links removed:

• assets.nyuchi.com 404s.
• status.mukoko.com has no DNS record at all.
• The clone URL was github.com/nyuchitech/mukoko; that org redirects, but the
  canonical URL is mukoko-dev/mukoko and is now used directly.
• The licence section linked ./LICENSE. No LICENSE file is committed. The
  section now says so plainly instead of linking a file that isn't there.

Added a CI badge (the workflow runs on push and PR to main) and five stack
badges; all six resolve.

Co-Authored-By: Claude Opus 5 (1M context) noreply@anthropic.com