Add jnsahaj-lumen devcontainer feature

[Copilot]

Adds a devcontainer feature for lumen, an AI-powered git diff viewer and commit message generator. Since lumen only publishes macOS binaries in GitHub releases, Linux installation uses cargo install lumen via rustup.

Changes

• src/jnsahaj-lumen/devcontainer-feature.json — Feature metadata; exposes a version option (default: latest)
• src/jnsahaj-lumen/install.sh — Installs Rust toolchain system-wide via rustup (to /usr/local/rustup + /usr/local/cargo) if not already present, then runs cargo install lumen [--version X.Y.Z]; symlinks binary into /usr/local/bin
• test/jnsahaj-lumen/test.sh — Smoke test: lumen --version
• .github/workflows/test.yaml — Added jnsahaj-lumen to both test-autogenerated and test-scenarios matrices

Usage

"features": {
    "ghcr.io/devcontainer-community/devcontainer-features/jnsahaj-lumen:1": {}
}

Pin to a specific version:

"features": {
    "ghcr.io/devcontainer-community/devcontainer-features/jnsahaj-lumen:1": {
        "version": "2.21.0"
    }
}

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:

• https://api.github.com/repos/jnsahaj/lumen/releases/latest
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (http 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

---

This section details on the original issue you should resolve

<issue_title>Create jnsahaj-lumen feature</issue_title>
<issue_description>Files:

src//devcontainer-feature.json
src//install.sh (make sure to set executable bit)
test//test.sh
.github/workflows/test.yaml

Releases:

https://github.com/jnsahaj/lumen/releases</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Create jnsahaj-lumen feature #136

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