snapshot: preserve backup UX, remote target setup, and docs updates

scripts/backup_create.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+cd "$ROOT_DIR"
+
+set -a
+. ./.env
+set +a
+
+timestamp="$(date +"%Y%m%d_%H%M%S")"
+backup_dir="${1:-$ROOT_DIR/backend/backups/backup_${timestamp}}"
+mkdir -p "$backup_dir"
+
+db_dump_path="$backup_dir/db.dump"
+media_archive_path="$backup_dir/media.tar.gz"
+meta_path="$backup_dir/backup_meta.env"
+checksums_path="$backup_dir/SHA256SUMS"
+
+docker compose exec -T db sh -lc "PGPASSWORD='$POSTGRES_PASSWORD' pg_dump -U '$POSTGRES_USER' -d '$POSTGRES_DB' -Fc --no-owner --no-privileges" > "$db_dump_path"
+tar -C "$ROOT_DIR/backend" -czf "$media_archive_path" media
+
+cat > "$meta_path" <<EOF
+BACKUP_CREATED_AT=$timestamp
+POSTGRES_DB=$POSTGRES_DB
+POSTGRES_USER=$POSTGRES_USER
+DB_DUMP_FILE=$(basename "$db_dump_path")
+MEDIA_ARCHIVE_FILE=$(basename "$media_archive_path")
+EOF
+
+(
+  cd "$backup_dir"
+  shasum -a 256 "$(basename "$db_dump_path")" "$(basename "$media_archive_path")" > "$checksums_path"
+)
+
+printf '%s\n' "$backup_dir"