feat: mysql-bkup v2 on bkupkit

MysQL backup and restore built on the shared bkupkit core:
streaming end to end, with no dump held in memory or written to
local disk.

docs/how-tos/restore-from-ssh.md

@@ -45,16 +45,17 @@ services:
       - DB_PORT=3306
       - DB_HOST=mysql
       - DB_NAME=database
-      - DB_USERNAME=username
+      - DB_USER=username
       - DB_PASSWORD=password
       ## SSH Configuration
-      - SSH_HOST_NAME=hostname
-      - SSH_PORT=22
-      - SSH_USER=user
-      - SSH_REMOTE_PATH=/home/jkaninda/backups
-      - SSH_IDENTIFY_FILE=/tmp/id_ed25519
+      - SFTP_HOST=hostname
+      - SFTP_PORT=22
+      - SFTP_USER=user
+      - REMOTE_PATH=/home/jkaninda/backups
+      - SFTP_IDENTITY_FILE=/tmp/id_ed25519
+      - SFTP_KNOWN_HOSTS=/config/known_hosts
       ## Optional: Use password instead of private key (not recommended)
-      #- SSH_PASSWORD=password
+      #- SFTP_PASSWORD=password
     # Ensure the mysql-bkup container is connected to the same network as your database
     networks:
       - web
@@ -70,5 +71,5 @@ networks:
 - **Supported File Formats**: The restore process supports `.sql`, `.sql.gz`, `.sql.gpg`, and `.sql.gz.gpg` files.
 - **SSH Path**: Use the `--path` flag to specify the folder on the SSH remote server where the backup file is located.
 - **Encrypted Backups**: If the backup is encrypted with GPG, ensure the `GPG_PASSPHRASE` environment variable is set for automatic decryption.
-- **SSH Authentication**: Use a private key (`SSH_IDENTIFY_FILE`) for SSH authentication instead of a password for better security.
+- **SSH Authentication**: Use a private key (`SFTP_IDENTITY_FILE`) for SSH authentication instead of a password for better security. Host keys are verified against `SFTP_KNOWN_HOSTS` (or set `SFTP_INSECURE_IGNORE_HOST_KEY=true`).
 - **Network Configuration**: Ensure the `mysql-bkup` container is connected to the same network as your database.