feat: Implement a new Dockerized PostgreSQL data synchronization service with cron scheduling.

sync/sync.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+# Sync PostgreSQL Debian → PostgreSQL Hostinger
+# Source  : frps:15432 (tunnel frp vers postgres Debian)
+# Destination : postgres_db (container existant sur Hostinger)
+
+set -e
+
+echo "=== SYNC START $(date) ==="
+
+PGPASSWORD=$SRC_PASS pg_dump \
+  -h "$SRC_HOST" -p "$SRC_PORT" \
+  -U "$SRC_USER" -d "$SRC_DB" \
+  --data-only --if-exists --clean \
+  --no-acl --no-owner \
+| PGPASSWORD=$DST_PASS psql \
+  -h "$DST_HOST" -p "$DST_PORT" \
+  -U "$DST_USER" -d "$DST_DB" \
+  --set ON_ERROR_STOP=0
+
+echo "=== SYNC DONE $(date) ==="