feat(2.0): Phase 5 — Betrieb, Observability + Politur

Backup: services/backup.py (Memory-SQLite inkl. WAL/SHM + Configs, retain 7)
+ deploy/backup.sh + POST /api/system/backup + GET /api/system/backups.
Services-Health: GET /api/system/services (aggregierte Reachability +
Observability-Links). Frontend: SystemView mit Dienste-Health + Backup-
Button + Links; Theme-Toggle (Hell/Dunkel, persistent).

Lokal verifiziert: Backup-Snapshot + services-Aggregat (TestClient),
Frontend-Build + Browser (Light-Mode bestaetigt via computed styles).
Damit Phasen 0-5 lokal fertig. Docs aktualisiert.

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

frontend/src/lib/api.ts

@@ -88,6 +88,11 @@ export interface SystemStatus {
   disk: { total: number; used: number; percent: number } | null
 }
 
+export interface ServicesResp {
+  services: { name: string; url: string; ok: boolean }[]
+  links: { engine_ui: string; gateway: string; hermes_webui: string }
+}
+
 export interface ConnectTool {
   label: string
   lang: string