fix(backup): proper backup/restore hooks + healthcheck start_period

- Add mysql_backup.sh: mysqldump to backup.sql.gz with proper restore hook
  (old --tab backup had no restore hook → restored backup silently lost DB data)
- Update db backupbot labels: pre-hook → /mysql_backup.sh backup,
  restore.post-hook → /mysql_backup.sh restore
- Fix app healthcheck start_period 1m → 15m (Ghost fresh-DB migration takes ~6-9min
  on slow hosts; old 1m caused migration lock deadlocks on deploy)
- Fix db healthcheck start_period 1m → 15m (InnoDB init on fresh data dir ~6-10min)
- Add MYSQL_BACKUP_VERSION=v1 to abra.sh

mysql_backup.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+# MySQL backup/restore hook for the `db` service. Invoked by backupbot-two via:
+#   backupbot.backup.pre-hook   = "/mysql_backup.sh backup"
+#   backupbot.backup.path       = "/var/lib/mysql/backup.sql.gz"
+#   backupbot.restore.post-hook = "/mysql_backup.sh restore"
+# Backup dumps the `ghost` DB to a single gzipped file inside the mysql data volume; backupbot
+# archives it. Restore reimports it. The previous recipe shipped a `mysqldump --tab` backup with NO
+# restore hook (and the mysql data volume itself was not backed up), so a restored backup silently
+# kept the live, un-restored DB state — data loss on restore.
+
+set -e
+
+BACKUP_FILE="/var/lib/mysql/backup.sql.gz"
+export MYSQL_PWD="$(cat "${MYSQL_ROOT_PASSWORD_FILE:-/run/secrets/db_password}")"
+DB_NAME="ghost"
+
+function backup {
+  mysqldump -u root --single-transaction --routines --triggers --databases "$DB_NAME" | gzip > "$BACKUP_FILE"
+}
+
+function restore {
+  # --databases dump carries CREATE DATABASE/USE + per-table DROP+CREATE (mysqldump default), so the
+  # reimport deterministically rebuilds every table from the archived dump.
+  gunzip -c "$BACKUP_FILE" | mysql -u root
+}
+
+$@