### Summary
1. update docker compose file to start NATS healthy
2. Add two commands
```
RAGFlow(admin)> live;
SUCCESS
RAGFlow(admin)> health;
+---------------+-------+
| field | value |
+---------------+-------+
| storage | ok |
| message_queue | ok |
| status | ok |
| db | ok |
| redis | ok |
| doc_engine | ok |
+---------------+-------+
```
---------
Signed-off-by: Jin Hai <haijin.chn@gmail.com>
## Summary
- Add Go REST support for `GET /api/v1/system/healthz`.
- Return Python-compatible `ok`/`nok` dependency fields for DB, Redis,
document engine, and storage.
- Return HTTP 200 only when all checks pass; otherwise return HTTP 500
with `_meta` failure details.
- Add focused service coverage for the unhealthy dependency response
when Go dependencies are not initialized.
## Scope
This is a small, isolated slice of #15240. It avoids current open
connector PRs (#15274, #15300, #15265, #15264), tenant/member PRs
(#15295, #15301, #15276), MCP PRs (#15281, #15253, #15254, #15260,
#15261, #15262), and the memory-message PR (#15256).
Refs #15240
