Add CI/CD pipeline with multi-version testing and Docker builds

[Copilot]

Implements automated building and testing of the zstd-nginx-module across multiple nginx versions and platforms.

CI Workflow

Matrix testing across:

• Nginx: 1.24.0, 1.25.3, 1.26.0
• Ubuntu: 20.04, 22.04

Jobs:

• Build nginx with zstd module and run Test::Nginx suite
• Validate multi-stage Docker builds
• Lint for whitespace and permissions

Caches nginx source for faster builds. Sets explicit contents: read token permissions.

Examples

Docker:

docker build -f example/Dockerfile -t nginx-zstd .
docker run -d -p 80:80 nginx-zstd

nginx.conf snippet:

http {
    zstd on;
    zstd_comp_level 3;
    zstd_min_length 256;
    zstd_types text/plain text/css application/json;
}

Files added:

• .github/workflows/ci.yml - GitHub Actions workflow
• example/Dockerfile - Multi-stage production build
• example/nginx.conf - Complete configuration with zstd settings
• example/README.md - Usage guide with manual build instructions
• CI_CD_IMPLEMENTATION.md - Implementation details

Updates README with CI badge and Docker quick-start.

[!WARNING]

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• nginx.org
  • Triggering command: wget -q REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Help me to write the CI/CD so that the zstd-nginx-module can be built in a Nginx.

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