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>

backend/services/backup.py

@@ -0,0 +1,51 @@
+"""
+Backup der „Verfassung" (Shared-Memory-SQLite) + aller Configs.
+Snapshot in einen Zeitstempel-Ordner; die letzten N bleiben erhalten.
+"""
+
+import shutil
+import time
+from pathlib import Path
+
+from config import CONFIG_PATH, GATEWAY_CONFIG_PATH, MEMORY_DB, MODELS_DIR
+
+BACKUP_DIR = Path(MODELS_DIR) / "mc2-backups"
+RETAIN = 7
+
+
+def _safe_copy(src: Path, dst_dir: Path) -> str | None:
+    try:
+        if src and src.exists():
+            shutil.copy2(src, dst_dir / src.name)
+            return src.name
+    except Exception:
+        pass
+    return None
+
+
+def backup_now() -> dict:
+    """Erstellt einen Snapshot (Memory-DB inkl. WAL/SHM + Configs). Alte Snapshots
+    über RETAIN hinaus werden entfernt."""
+    ts = time.strftime("%Y%m%d-%H%M%S")
+    dst = BACKUP_DIR / ts
+    dst.mkdir(parents=True, exist_ok=True)
+    saved = []
+    for src in (MEMORY_DB, Path(str(MEMORY_DB) + "-wal"), Path(str(MEMORY_DB) + "-shm"),
+                CONFIG_PATH, GATEWAY_CONFIG_PATH):
+        if (name := _safe_copy(src, dst)):
+            saved.append(name)
+    # Aufräumen: nur die letzten RETAIN Snapshots behalten.
+    snaps = sorted([p for p in BACKUP_DIR.iterdir() if p.is_dir()], reverse=True)
+    for old in snaps[RETAIN:]:
+        shutil.rmtree(old, ignore_errors=True)
+    return {"ok": bool(saved), "snapshot": ts, "files": saved, "dir": str(dst)}
+
+
+def list_backups() -> list[dict]:
+    if not BACKUP_DIR.exists():
+        return []
+    out = []
+    for p in sorted([d for d in BACKUP_DIR.iterdir() if d.is_dir()], reverse=True):
+        files = [f.name for f in p.iterdir() if f.is_file()]
+        out.append({"snapshot": p.name, "files": files})
+    return out