Add add-script feature

[Copilot]

Companion to run-script that permanently places a script at /usr/local/bin/<name> without executing it during the devcontainer build.

Changes

• src/add-script/devcontainer-feature.json — three options: name (target filename), url (remote script), script (inline text)
• src/add-script/install.sh — writes script to /usr/local/bin/<name>, sets chmod 755, never executes it; gracefully no-ops if name/source is absent; errors on url+script conflict
• src/add-script/NOTES.md — feature documentation
• test/add-script/test.sh — baseline test
• README.md — added row in alphabetical order

Usage

"features": {
    "ghcr.io/devcontainer-community/devcontainer-features/add-script:1": {
        "name": "my-setup",
        "script": "#!/bin/bash\napt-get install -y ripgrep"
    }
}

The script is available as my-setup in the container but must be invoked explicitly — it is not run at build time.

Differences from run-script

	run-script	add-script
Script location	temp file, deleted after use	/usr/local/bin/<name> (permanent)
Executed during install	yes	no
Extra option	—	name (required)