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registry Dockerfile, and marks the dated design specs superseded where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.

PRODUCT.md

@@ -7,22 +7,21 @@ product
 ## Users
 
 A single technical operator (a developer) managing every interactive shell and
-agent — Claude Code, opencode, plain bash — running across multiple machines.
-The job-to-be-done: from any device (laptop, desktop, **phone**), get an
-accurate at-a-glance picture of all live sessions across all hosts, then attach
-to one and drive its terminal. Usage is often glance-and-go: checking on a
+agent — Claude Code, opencode, plain bash — running on a machine. The
+job-to-be-done: from any device (laptop, desktop, **phone**), get an accurate
+at-a-glance picture of all live sessions on that host, then attach to one and
+drive its terminal. Usage is often glance-and-go: checking on a
 long-running agent, killing a stray session, or hopping into a shell mid-task.
 Mobile-first is a hard requirement — touch targets, viewport-fit safe areas,
 and bottom-sheet modals already reflect this.
 
 ## Product Purpose
 
-Maestro is a unified terminal-session orchestrator: one place to see and attach
-to every interactive session running across every machine the operator cares
-about. tmux for persistence, WebSocket for transport, a daemon-per-host
-federated by a small always-on registry. The web UI is the browser face of
-that system — it renders the cross-host session catalog and provides the attach
-terminal (xterm.js). Success = the operator trusts the picture is accurate and
+Maestro is a terminal-session orchestrator: one place to see and attach to
+every interactive session running on a machine. tmux for persistence,
+WebSocket for transport, one daemon per host. The web UI is the browser face of
+that system — it renders the session catalog and provides the attach terminal
+(xterm.js). Success = the operator trusts the picture is accurate and
 current, and can get from "open the page" to "typing in the right session" in
 seconds, on any device.
 
@@ -51,14 +50,14 @@ efficient, calm / uncluttered, with earned moments of delight.
 ## Design Principles
 
 1. **The scan is the product.** Optimize for instant comprehension of "what's
-   running, where, and is it healthy" across many sessions and hosts. Status
-   legibility beats everything else.
+   running, where, and is it healthy" across many sessions. Status legibility
+   beats everything else.
 2. **Calm under load.** Stay uncluttered whether there are 3 sessions or 300;
    hierarchy and grouping carry the weight, not color-shouting every row.
 3. **Fast and keyboard-literate.** Low-friction, efficient, gets out of the
    way; honor keyboard navigation, don't make the operator hunt.
 4. **Monospace as identity.** Treat the mono/sans pairing as deliberate brand
-   typography, not just terminal output. Ids, hosts, counts, and state read as
+   typography, not just terminal output. Ids, paths, counts, and state read as
    precise technical data.
 5. **Earned delight.** Personality lives in motion and micro-detail (live-status
    pulse, attach transitions, cursor cues), never in noise — always craft.