PR: Add Bun Package Helper (bun-package)

[trevordcampbell]

Summary

• Add bun-package: Installs a single package globally via Bun.
• Provide parity with the existing npm-package helper while following Bun best practices.
• Add tests for Debian / Ubuntu / Alpine installs and a pinned-version scenario.

Motivation

• Offer first-class package installation helpers for Bun, mirroring the existing npm helper features to streamline internal reuse and user workflows.
• Keep behavior consistent with repository standards and helper-first patterns, with small layers and clear skip semantics.

Features Added

• src/bun-package/
  • Purpose: Install a single package globally via Bun.
  • Behavior:
    • Exports BUN_INSTALL=/usr/local so binaries land in /usr/local/bin.
    • Accepts bare names and optional npm:-prefixed names (Bun defaults to npm registry).
    • Skip-if-installed semantics:
      • For latest installs, skips when package already present.
      • For pinned installs, skips only when exact <name>@<version> is present.
    • Supports non-npm specs (git/URL/GitHub shorthand); nameHint assists skip checks when the displayed name differs.
    • Includes basic retry logic around bun add to mitigate transient registry 5xx errors.
    • Requires Bun to be present (via bun feature); installsAfter references bun.
  • Options:
    • package: string (required)
    • version: string (default latest)
    • nameHint: string (optional)

Intended Use

• bun-package: Helper-oriented, ideal for downstream features to install a single tool or for precise control (incl. non-npm specs using nameHint).

Usage Examples

• Single package (latest):

"features": {
  "ghcr.io/devcontainers-extra/features/bun:1": {},
  "ghcr.io/devcontainers-extra/features/bun-package:1": {
    "package": "@vercel/turbo"
  }
}

• Single package (pinned):

"features": {
  "ghcr.io/devcontainers-extra/features/bun:1": {},
  "ghcr.io/devcontainers-extra/features/bun-package:1": {
    "package": "@vercel/turbo",
    "version": "2.5.6"
  }
}

Tests

• Scenarios (bun-package):
  • Debian/Ubuntu/Alpine TypeScript install (latest)
  • Angular CLI install
  • Pinned install: TypeScript 5.5.4 (asserts reported version)

Note: Existing-package installation testing scenarios for bun-package are deferred for now (difficult to model a preinstalled global package in a clean base image without a published multi-package helper). They can be re-enabled later once a reliable path is available / a future bun-packages multi-package installer feature is available to fill that gap.

Docs

• Auto-generated README for the feature.
• NOTES.md for bun-package includes:
  • Optional npm: prefix usage
  • Behavior and skip semantics
  • Non-npm sources and nameHint

Compatibility

• Coexists with Node / npm helper features.
• Global installs target /usr/local/bin for consistent PATH.

Security/Robustness

• nanolayer usage keeps layers small where applicable.
• No unnecessary PATH / profile mutations; relies on Bun defaults with explicit BUN_INSTALL.
• Adds retry / backoff around bun add to reduce flakiness from transient registry errors.

Checklist

• Code matches project style; helpers used where applicable
• Metadata (devcontainer-feature.json) includes options and installsAfter
• Tests cover Debian / Ubuntu / Alpine installs and pinned version scenario
• Lints are clean