GitHub Stars API endpoint returns 401 — star chart feature broken for all repos

## Bug Description

The GitHub Stars feature on firegraph.so is completely broken. When attempting to fetch star history for any repository, the `/api/githubStars` endpoint returns an HTTP 500 error wrapping a 401 Unauthorized response from the GitHub API.

## Steps to Reproduce

1. Visit [firegraph.so](https://firegraph.so)
2. Click **GitHub Stars**
3. Enter any valid repository URL (e.g., `https://github.com/mendableai/firecrawl`)
4. Click Submit

## Expected Behavior

A star history chart should render showing the repo's GitHub stars over time.

## Actual Behavior

The request fails with a 500 error. No chart is displayed.

**Evidence via `curl`:**

```bash
curl 'https://firegraph.so/api/githubStars?repo=mendableai/firecrawl'
```

Returns:

```json
{"error":"Request failed with status code 401"}
```

HTTP status code: **500**

## Likely Cause

The GitHub API token used by the deployed backend has expired or is missing, causing all authenticated GitHub API requests to fail with `401 Unauthorized`. This is then surfaced to the client as a `500` internal server error.

## Additional Notes

- The rest of the site loads fine — only the star history API is affected.
- **CSV import still works correctly**, confirming the issue is isolated to the GitHub API integration.
- This affects all repositories, not just specific ones.