docs(maestro): describe the single-host architecture

Rewrites CLAUDE.md as the current-architecture reference, drops the
registry from INSTALL/PRODUCT/DESIGN and the web README, deletes the
registry Dockerfile, and marks the dated design specs superseded where
they describe the registry, JWT auth, or cross-host attach.

The installer loses its configure step — every config field now has a
default, so a daemon starts with no config file at all.

Justfile

@@ -8,7 +8,7 @@ web:
 
 # Run the web bundle in dev mode against a local daemon — Vite serves the
 # frontend with HMR, and `/api/*` is proxied directly to the daemon at
-# 127.0.0.1:7070 (or wherever $MAESTRO_REGISTRY points; see vite.config.ts).
+# 127.0.0.1:7070 (see vite.config.ts).
 web-dev:
     pnpm -C web install
     pnpm -C web dev