Add database backup script

scripts/backup-db.sh copies the remote DB via scp to ./backups/
with a timestamp. Backups older than 30 days are auto-deleted.
Backup directory is gitignored.

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

scripts/backup-db.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# Erstellt ein Backup der Krafttrainer-Datenbank vom Server.
+# Verwendung: ./scripts/backup-db.sh [user@host]
+#
+# Standard-Ziel: christoph@192.168.1.118
+# Backups werden in ./backups/ gespeichert.
+
+set -euo pipefail
+
+REMOTE="${1:-christoph@192.168.1.118}"
+REMOTE_DB="/home/christoph/fitnesspad/krafttrainer.db"
+BACKUP_DIR="$(dirname "$0")/../backups"
+TIMESTAMP="$(date +%Y-%m-%d_%H-%M-%S)"
+BACKUP_FILE="${BACKUP_DIR}/krafttrainer_${TIMESTAMP}.db"
+
+mkdir -p "$BACKUP_DIR"
+
+echo "Backup von ${REMOTE}:${REMOTE_DB} ..."
+scp "${REMOTE}:${REMOTE_DB}" "${BACKUP_FILE}"
+echo "Gespeichert: ${BACKUP_FILE}"
+
+# Alte Backups (älter als 30 Tage) löschen
+find "$BACKUP_DIR" -name "krafttrainer_*.db" -mtime +30 -delete 2>/dev/null && true