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>

ecosystem.config.cjs

@@ -70,5 +70,11 @@ module.exports = {
       args: 'run src/servers/sidecar/slskd/index.ts',
       watch: false,
     },
+    {
+      name: 'officer-headscale',
+      script: 'bun',
+      args: 'run src/servers/sidecar/headscale/index.ts',
+      watch: false,
+    },
   ],
 };