Curl not working anymore.

### Description
The current README suggests using `curl` for the health check. However, the `appwrite/browser` Dockerfile does not install `curl`.

As a result, the documented health check fails because the required system tools are missing.

### Proposed Fix
Since the `bun` binary is present, the health check should utilize Bun's native `fetch` capabilities.

**Replace:**
`curl http://localhost:3000/v1/health`

--

`bun -e "fetch(''http://127.0.0.1:3000/v1/health'').then(r=>process.exit(r.status===200?0:1)).catch(()=>process.exit(1))"` worked for me in my Coolify environment.

Greeting 🫶

### 👀 Have you spent some time to check if this issue has been raised before?

- [x] I checked and didn't find similar issue

### 🏢 Have you read the Code of Conduct?

- [x] I have read the [Code of Conduct](https://github.com/appwrite/.github/blob/main/CODE_OF_CONDUCT.md)