fix: Restore all files lost during destructive rebase

A previous `git pull --rebase origin main` dropped 177 local commits,
losing 3400+ files across admin-v2, backend, studio-v2, website,
klausur-service, and many other services. The partial restore attempt
(660295e2) only recovered some files.

This commit restores all missing files from pre-rebase ref 98933f5e
while preserving post-rebase additions (night-scheduler, night-mode UI,
NightModeWidget dashboard integration).

Restored features include:
- AI Module Sidebar (FAB), OCR Labeling, OCR Compare
- GPU Dashboard, RAG Pipeline, Magic Help
- Klausur-Korrektur (8 files), Abitur-Archiv (5+ files)
- Companion, Zeugnisse-Crawler, Screen Flow
- Full backend, studio-v2, website, klausur-service
- All compliance SDKs, agent-core, voice-service
- CI/CD configs, documentation, scripts

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/backup-cron.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+# Automatisches Backup-Skript für Cron
+# Füge zu crontab hinzu: 0 2 * * * /path/to/backup-cron.sh
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_DIR="$(dirname "$SCRIPT_DIR")"
+
+cd "$PROJECT_DIR"
+
+# Backup ausführen und Log schreiben
+export BACKUP_DIR="$PROJECT_DIR/backups"
+"$SCRIPT_DIR/backup.sh" >> "$PROJECT_DIR/backups/backup.log" 2>&1
+
+# Bei Fehler eine Benachrichtigung senden (optional)
+if [ $? -ne 0 ]; then
+    echo "Backup failed at $(date)" >> "$PROJECT_DIR/backups/backup.log"
+fi