vault: offline backup script (pull accounts + worlds to local snapshots)

The vault's user data (argon2 hashes + saved worlds) only lives on the
VPS and isn't in git. backup.sh pulls /opt/mrpgi-vault/data down as a
timestamped tarball, keeps the 30 newest, and documents the restore
path in its header.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

mrpgi-vault/backup.sh

@@ -0,0 +1,34 @@
+#!/bin/sh
+# Offline backup of the live MRPGI vault — the accounts (argon2 hashes) and
+# saved worlds that ONLY exist on the dealgod VPS and are NOT in git.
+#
+# Pulls /opt/mrpgi-vault/data down to this machine as a timestamped tarball,
+# keeping the 30 most recent snapshots. Run it from anywhere.
+#
+#   ./mrpgi-vault/backup.sh
+#   MRPGI_BACKUP_DIR=/some/where ./mrpgi-vault/backup.sh   # override location
+#
+# Restore onto the VPS (if the box is ever rebuilt):
+#   tar -xzf vault-YYYYMMDD-HHMMSS.tar.gz            # gives ./data
+#   scp -r data root@100.94.195.115:/opt/mrpgi-vault/
+#   ssh root@100.94.195.115 'docker restart mrpgi-vault'
+set -e
+
+REMOTE="${MRPGI_VAULT_REMOTE:-root@100.94.195.115:/opt/mrpgi-vault/data}"
+DEST="${MRPGI_BACKUP_DIR:-$HOME/MRPGI-vault-backups}"
+KEEP=30
+
+mkdir -p "$DEST"
+STAMP=$(date +%Y%m%d-%H%M%S)
+TMP=$(mktemp -d)
+trap 'rm -rf "$TMP"' EXIT
+
+scp -q -r "$REMOTE" "$TMP/data"
+tar -czf "$DEST/vault-$STAMP.tar.gz" -C "$TMP" data
+
+# prune to the newest $KEEP snapshots
+ls -1t "$DEST"/vault-*.tar.gz 2>/dev/null | tail -n +$((KEEP + 1)) | while read -r old; do rm -f "$old"; done
+
+COUNT=$(ls -1 "$DEST"/vault-*.tar.gz 2>/dev/null | wc -l | tr -d ' ')
+SIZE=$(du -h "$DEST/vault-$STAMP.tar.gz" | cut -f1)
+echo "backed up -> $DEST/vault-$STAMP.tar.gz ($SIZE; $COUNT snapshots kept)"