add the officer-headscale sidecar and its server registry ui

officer-headscale owns the whole Headscale contract: the registered servers and
their admin api keys, the >=0.29 version floor, and every multi-call composition
the ui needs. the platform side is auth+forward only and holds no headscale
credentials, so the existing /api/vpn/enroll route and its HEADSCALE_* env vars
are untouched and unrelated.

officer manages many servers rather than one. the owner registers each with a url
and a key generated on that server and switches between them; exactly one is
active, enforced by a partial unique index rather than by convention. keys are
encrypted at rest and never leave the sidecar — the list projection cannot return
one. registration validates before it saves: an unauthenticated GET /version to
prove something headscale-shaped is there and meets the floor, then an
authenticated call to prove the key works. an edit that moves either half
re-validates.

there is deliberately no transparent /api/v1/* passthrough. headscale serialises
every uint64 as a json string and its rest shape moved repeatedly below 0.29;
proxying raw would push all of that into the browser, which is the mistake the
soulseek panels made with 37 raw upstream calls.

the /headscale workspace is nav + view over the panel system. only the servers
section is implemented — nodes, users and pre-auth keys say so plainly rather
than rendering an empty table that reads as a failed fetch.

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

src/apps/officer-web/Screens/Dashboard/Layout/Dock.tsx

@@ -134,6 +134,7 @@ import {
   Music,
   Activity,
   Radio,
+  Network,
 } from 'lucide-react';
 
 export const ALL_DOCK_ITEMS: DockItem[] = [
@@ -143,6 +144,7 @@ export const ALL_DOCK_ITEMS: DockItem[] = [
   { label: 'Chat', to: '/chat', icon: MessageCircle, color: '#60a5fa' },
   { label: 'Music', to: '/music', icon: Music, color: '#22c55e' },
   { label: 'Soulseek', to: '/soulseek', image: '/slskd.png', color: '#ffffff' },
+  { label: 'Headscale', to: '/headscale', icon: Network, color: '#818cf8' },
   { label: 'Editor', to: '/code-editor', icon: Code, color: '#a78bfa' },
   { label: 'Plans', to: '/plans', icon: FileText, color: '#f472b6' },
   { label: 'Jobs', to: '/jobs', icon: Workflow, color: '#14b8a6' },