feat: complete n8n stack setup

Docker Compose stack (n8n, PostgreSQL 16, Redis 7, 1 worker) with:
- nginx local proxy on port 8088, YunoHost TLS termination config
- helper scripts: backup/restore/import/export/update
- .env.example, README with architecture, ops commands, to-do list

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

scripts/backup-n8n.sh

@@ -0,0 +1,48 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ROOT="$(dirname "$SCRIPT_DIR")"
+COMPOSE="$ROOT/compose/docker-compose.yml"
+ENV="$ROOT/.env"
+BACKUP_DIR="$ROOT/backups"
+MAX_BACKUPS=2
+
+# shellcheck source=/dev/null
+source "$ENV"
+
+TIMESTAMP=$(date +"%Y%m%d_%H%M%S")
+TARGET="$BACKUP_DIR/backup_$TIMESTAMP"
+mkdir -p "$TARGET"
+
+echo "[backup] Starte Backup → $TARGET"
+
+# PostgreSQL dump
+echo "[backup] Datenbank-Dump..."
+docker compose -f "$COMPOSE" exec -T postgres \
+  pg_dump -U "$POSTGRES_USER" "$POSTGRES_DB" \
+  > "$TARGET/postgres.sql"
+
+# n8n data
+echo "[backup] n8n Datendirectory..."
+tar -czf "$TARGET/n8n-data.tar.gz" -C "$ROOT/data" n8n
+
+# Compose-Konfiguration
+echo "[backup] Compose + .env..."
+cp "$COMPOSE" "$TARGET/docker-compose.yml"
+cp "$ENV" "$TARGET/.env"
+
+echo "[backup] Backup abgeschlossen: $TARGET"
+
+# Retention: nur die letzten MAX_BACKUPS behalten
+EXISTING=$(ls -dt "$BACKUP_DIR"/backup_* 2>/dev/null)
+COUNT=$(echo "$EXISTING" | wc -l)
+if [ "$COUNT" -gt "$MAX_BACKUPS" ]; then
+  TO_DELETE=$(echo "$EXISTING" | tail -n +"$((MAX_BACKUPS + 1))")
+  echo "[backup] Lösche alte Backups:"
+  echo "$TO_DELETE"
+  echo "$TO_DELETE" | xargs rm -rf
+fi
+
+echo "[backup] Fertig. Aktuelle Backups:"
+ls -lht "$BACKUP_DIR"