feat: multi-database backup, HTTP API endpoints, admin panel UI

- backup CLI: add --all-databases, --database, --data-root flags
- backup format: tar.gz with databases/<name>/ + backup.json metadata
- HTTP API: new endpoints /databases, /backup, /backups, /restore
- HTTP API: database switching via X-Database header
- Admin panel: database selector dropdown, Databases tab, Backups tab
- Admin panel: backup/restore UI with fetch() to new endpoints
- Update deps: hunos 1.3.0, jwt-nim-baraba 2.1.0
- Docker: backup cron uses --all-databases --data-root=/data/databases
- Docs: update api-http.md, protocol.md with correct endpoints
- OpenAPI spec updated to v1.1.6

Known limitation: DELETE /databases disabled due to ORC SIGSEGV
in LSMTree.close(). Use SQL DROP DATABASE instead.

docker-compose.prod.yml

@@ -102,8 +102,8 @@ services:
       sh -c '
         while true; do
           sleep 86400;
-          /app/backup backup --data-dir=/data --output=/backups/baradb_$$(date +%Y%m%d_%H%M%S).tar.gz --level=6;
-          /app/backup cleanup --keep=7;
+          /app/backup backup --all-databases --data-root=/data/databases --output=/backups/baradb_$$(date +%Y%m%d_%H%M%S).tar.gz --level=6;
+          /app/backup cleanup --data-root=/data/databases --keep=7;
         done
       '
     volumes: