fix: Gitea Traefik routing and connection pool optimization

- Remove middleware reference from Gitea Traefik labels (caused routing issues)
- Optimize Gitea connection pool settings (MAX_IDLE_CONNS=30, authentication_timeout=180s)
- Add explicit service reference in Traefik labels
- Fix intermittent 504 timeouts by improving PostgreSQL connection handling

Fixes Gitea unreachability via git.michaelschiemer.de

deployment/stacks/postgresql-production/scripts/backup-entrypoint.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+set -e
+
+echo "🔄 PostgreSQL Backup Service Starting..."
+echo "📅 Backup Schedule: ${BACKUP_SCHEDULE}"
+echo "🗑️  Retention: ${BACKUP_RETENTION_DAYS} days"
+
+# Install cronie for scheduled backups
+apk add --no-cache dcron
+
+# Create cron job
+echo "${BACKUP_SCHEDULE} /scripts/backup.sh >> /var/log/backup.log 2>&1" > /etc/crontabs/root
+
+# Ensure backup directory exists
+mkdir -p /backups
+
+# Run initial backup
+echo "🚀 Running initial backup..."
+/scripts/backup.sh
+
+# Start cron in foreground
+echo "✅ Backup service ready - cron daemon starting"
+crond -f -l 2