offscale is a plugin

headscale leaves the platform. 45 files move to plugins/offscale/ and the
platform stops knowing it exists.

  api/router.ts   the thin auth-gated proxy, now at /api/offscale
  sidecar/        18 files, the whole headscale contract and its admin keys
  db/             schema + queries, offscale_servers
  web/            26 files as panels and a layout — no screen, per the rule

removed from the platform: the hono mount, the `headscale` capability, the
App.tsx route pair, the screen and its barrel, the AppRegistry spread, the
officerdev re-exports, the dock tile, the page-title rule, and both database
barrels. tsgo is clean and nothing references it.

the imports tell the story of what the plugin↔host API actually is. the sidecar
takes @@/sidecar/protocol, @@/sidecar/connect, @@/data-path and
@@/officer-url.mjs; the queries take officerdb/db and officerdb/crypto; the
schema takes officerdb/auth/schema for the one reference a plugin may make; the
web half takes useClient, copyToClipboard, WorkspaceView and TerminalView from
the officerdev barrel. all of it resolves because a plugin lives inside the repo
— no publishing, no version negotiation.

AND IT FOUND A REAL BUG IN THE INSTALLER. createSidecarProxy learns its port
from a one-shot `<name>:server` event and subscribes when the plugin's router is
first imported — at mount. install started the sidecar BEFORE mounting, so the
announcement fired into a void: process online, routes mounted, every request
answering `503 sidecar not available` until something forced a reconnect. it
would have hit every plugin with an http sidecar. `example` never caught it
because it has no listener to announce.

install and enable now mount before starting; disable still unmounts before
stopping. neither direction leaves a mounted route in front of a sidecar that
cannot be reached.

verified live: /api/offscale/_officer/servers answers {"servers":[]}, /offscale
and /offscale/nodes serve, the old /api/headscale is 404, the offscale
capability is registered from the manifest, and officer-offscale is online.

757 pass, same 10 pre-existing failures.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

plugins/offscale/web/HeadscaleServerPicker.tsx

@@ -0,0 +1,60 @@
+import { Check, Network, Plus } from 'lucide-react';
+import { Link } from 'react-router';
+import { headscaleSectionPath } from './shared';
+import { useHeadscaleServers } from './useHeadscaleServers';
+
+// Top-left panel of the /headscale workspace: which server everything else acts on.
+//
+// It is its own panel rather than a block inside HeadscaleNav because the two answer different questions —
+// "which server" and "which section" — and only one of them is navigation. Activating a server is a mutation
+// (a DB write that re-scopes every other query), so these stay buttons with no URL of their own, while the
+// section list below is real links.
+//
+// Every registered server is listed, including when there is only one: the panel's whole job is to say what
+// the rest of the screen is talking to, and a picker that hides itself at one server makes that invisible.
+
+export const HeadscaleServerPicker = () => {
+  const { servers, active, activate, isLoading } = useHeadscaleServers();
+
+  return (
+    <div className="flex h-full flex-col overflow-y-auto bg-muted/30">
+      <div className="flex items-center gap-3 px-4 py-4">
+        <div className="flex h-9 w-9 items-center justify-center rounded-xl bg-indigo-500/15 text-indigo-400 ring-1 ring-black/5">
+          <Network className="h-5 w-5" />
+        </div>
+        <div className="min-w-0">
+          <div className="truncate text-sm font-semibold leading-tight">Headscale</div>
+          <div className="truncate text-xs text-muted-foreground">{active ? active.name : 'no server'}</div>
+        </div>
+      </div>
+
+      <div className="flex flex-col gap-0.5 px-2 pb-3">
+        {servers.map((server) => (
+          <button
+            key={server.id}
+            type="button"
+            onClick={() => !server.isActive && activate.mutate(server.id)}
+            disabled={activate.isPending}
+            title={server.url}
+            className={`flex items-center gap-2 rounded-lg px-3 py-1.5 text-left text-xs transition-colors ${
+              server.isActive ? 'bg-muted font-medium text-foreground' : 'text-muted-foreground hover:bg-muted'
+            }`}
+          >
+            <Check className={`h-3.5 w-3.5 shrink-0 ${server.isActive ? 'text-primary' : 'opacity-0'}`} />
+            <span className="min-w-0 flex-1 truncate">{server.name}</span>
+          </button>
+        ))}
+
+        {servers.length === 0 && !isLoading && (
+          <Link
+            to={headscaleSectionPath('servers')}
+            className="flex items-center gap-2 rounded-lg px-3 py-1.5 text-xs text-muted-foreground transition-colors hover:bg-muted hover:text-foreground"
+          >
+            <Plus className="h-3.5 w-3.5 shrink-0" />
+            Register a server
+          </Link>
+        )}
+      </div>
+    </div>
+  );
+};