Helm repository URL resolves to apache.github.io, but hostname cannot be resolved

# Title

Unable to add APISIX Helm repository: `apache.github.io` cannot be resolved

# Description

## Problem

Adding the APISIX Helm repo fails for both URLs:

```bash
helm repo add apisix-dev https://charts.apiseven.com
helm repo add apisix-dev https://apache.github.io/apisix-helm-chart
```

Error:

```text
Error: looks like "..." is not a valid chart repository or cannot be reached: Get "https://apache.github.io/apisix-helm-chart/index.yaml": dial tcp: lookup apache.github.io: no such host
```

## Expected behavior

The Helm repository should be added successfully.

## Actual behavior

Helm attempts to fetch:

```text
https://apache.github.io/apisix-helm-chart/index.yaml
```

but DNS resolution for `apache.github.io` fails.

## Request

Please confirm the correct APISIX Helm repository URL and whether the current one is outdated or broken.

Start by reproducing both `helm repo add` commands from the issue and verify whether `charts.apiseven.com` and `apache.github.io/apisix-helm-chart/index.yaml` resolve and respond. Done means confirming the supported repository URL or identifying the outdated or broken endpoint; no repository file or test is named in the report.

Written by the indexing model from the issue text.