fix: install curl in Docker image for healthcheck

[iamgurjitsingh]

The HEALTHCHECK command in the Dockerfile was using curl, but curl is not available by default in the nginx:stable-alpine base image. This caused the health checks to always fail.

This commit adds curl installation using apk to ensure the healthcheck works correctly.

[azurejelly]

curl is already available by default on nginx:stable-alpine:

$ docker run -it --name "nginx" -d -p 80:80 nginx:stable-alpine
ffb7bdd44673dbe9997be335055036d14f0bedef955efed280ebc495ccd1b34a

$ docker exec -it nginx /bin/sh
/ # curl
curl: try 'curl --help' or 'curl --manual' for more information
/ # 

plus, the healthcheck does work:

root@marisa:~# docker inspect --format='{{json .State.Health}}' vert | jq
{
  "Status": "healthy",
  "FailingStreak": 0,
  "Log": [
    {
      "Start": "2025-12-03T12:09:59.497996692Z",
      "End": "2025-12-03T12:09:59.552074748Z",
      "ExitCode": 0,
      "Output": ""
    },
    {
      "Start": "2025-12-03T12:10:29.554858192Z",
      "End": "2025-12-03T12:10:29.599120287Z",
      "ExitCode": 0,
      "Output": ""
    },
    {
      "Start": "2025-12-03T12:10:59.600134551Z",
      "End": "2025-12-03T12:10:59.650502304Z",
      "ExitCode": 0,
      "Output": ""
    },
    {
      "Start": "2025-12-03T12:11:29.650982581Z",
      "End": "2025-12-03T12:11:29.69597203Z",
      "ExitCode": 0,
      "Output": ""
    },
    {
      "Start": "2025-12-03T12:11:59.697033642Z",
      "End": "2025-12-03T12:11:59.75156943Z",
      "ExitCode": 0,
      "Output": ""
    }
  ]
}

[iamgurjitsingh]

Thanks @azurejelly I also verify the same.