helmd hub: central server på Pi5 + agent-uplink + helmd ctl + web-login

Hub-läge i samma binär (doc/hub-plan.md): agenter ansluter utåt med
delad agent-nyckel (hub-sektion i config.json), web-/CLI-klienter
loggar in (lokala konton, pbkdf2; Authenticator-interface för LDAP
senare) och styr alla agenters sessioner via proxy + merged SSE.
Webbklienten autodetekterar hub/local via /api/mode. Nya kommandon:
helmd hub [setpass|users|agentkey], helmd ctl (login/agents/sessions/
prompt/screen/answer/events …). Enhetstester + scripts/run-hub-smoke.sh
(15-stegs e2e: hub + agent + ctl).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011KikHkfCiC3yELbsMN8fT9

helmd/web/style.css

@@ -77,6 +77,14 @@ nav { display: flex; gap: 4px; flex: 1; }
   width: 240px; border-right: 1px solid var(--border); background: var(--bg2);
   display: flex; flex-direction: column; padding: 10px; gap: 8px; overflow-y: auto;
 }
+.agent-bar { display: flex; flex-direction: column; gap: 4px; }
+.agent-bar label { color: var(--muted); font-size: 0.85rem; }
+.agent-bar select {
+  background: var(--bg3); color: var(--fg); border: 1px solid var(--border);
+  border-radius: 7px; padding: 7px 8px; font: inherit; width: 100%;
+}
+.agent-bar select:focus { outline: none; border-color: var(--accent); }
+#agentKeyOut { word-break: break-all; user-select: all; }
 .sess-head { display: flex; justify-content: space-between; align-items: center; color: var(--muted); }
 .sess-item {
   padding: 10px 12px; border-radius: 7px; cursor: pointer; border: 1px solid transparent;