feat(2.0): W8 — Wartung (OS/Engine/Modell-Updates, Restart, Reboot, Logs)

services/maintenance.py + routers/maintenance.py: updates-Badge (apt/Engine-
Release/dyn. Modell-Upgrades via discover), os-update + engine-update als
jobengine-Jobs, system-/user-aware Restart (llama-swap via sudo -n NOPASSWD),
reboot, logs (journalctl). Frontend: Wartungs-Block in SystemView mit Badge,
Buttons + Modell-Upgrade-Vorschlaegen. Passwortfrei (sudo -n).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/api.ts

@@ -102,6 +102,13 @@ export interface ServicesResp {
   links: { engine_ui: string; gateway: string; hermes_webui: string }
 }
 
+export interface UpdatesResp {
+  os: number
+  engine: number
+  models: number
+  model_list: { role: string; title: string; repo: string }[]
+}
+
 export interface ConnectTool {
   label: string
   lang: string