saving a connection now tells the other panels

reported on the first successful save: everything still showed no data and the
form stayed open, and a manual page refresh was the only way through.

two faults, one report. the form did not close itself — nothing cleared
?config, so a save left the settings view sitting on top of a plugin that now
worked. and the two reader panels are SIBLINGS in a workspace layout: they are
mounted independently, neither owns the other, and ConnectionPanel cannot call
into them. so they went on showing the failure they had loaded back when no
connection existed.

a channel is the sanctioned answer for exactly this — docs/navigation-audit.md
puts addressable state in the URL and leaves channels for "something changed,
re-read it". nobody wants to link to the moment after a save.

the nonce is a plain module counter, copied deliberately from officerdev's
channels.ts along with the reason: setSignal(n => n + 1) applies against the
value captured at render, so two bumps in one render window both compute
snapshot + 1 and the second overwrites the first — and nobody re-reads.
Date.now() is the same bug at millisecond scale.

disconnect bumps it too. the panels must stop showing hosts they can no longer
reach.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Officer-Session: 656f5c85-e49a-4f1f-b9f3-042a04b4d043

web/HostsPanel.tsx

@@ -4,6 +4,7 @@ import { useClient } from "hooks/useClient";
 import { useSearchParams } from "react-router";
 import { ConnectionPanel } from "./ConnectionPanel";
 import { readableError } from "./errors";
+import { useConnectionChanged } from "./channel";
 
 /**
  * The proxy hosts, which is the thing anybody opens this plugin to see.
@@ -66,6 +67,9 @@ export const HostsPanel = () => {
   // `?config=1` is the settings page; an unconfigured plugin shows it whether or not it was asked for.
   // In the URL rather than in state, so it survives a refresh and can be linked to — `docs/navigation-audit.md`.
   const configuring = params.get("config") === "1";
+  // Re-read when the connection is saved or removed. Named as an effect dependency below — that IS the
+  // subscription; there is nothing to unsubscribe from.
+  const [connectionSignal] = useConnectionChanged();
 
   const load = useCallback(async () => {
     try {
@@ -79,7 +83,7 @@ export const HostsPanel = () => {
 
   useEffect(() => {
     void load();
-  }, [load]);
+  }, [load, connectionSignal]);
 
   const toggle = async (host: ProxyHost) => {
     setBusy(host.id);