feat!: convert to typescript

[michaelmalave]

Summary

This PR replaces the Ruby devcenter gem with @heroku-cli/heroku-cli-plugin-devcenter, a Node 20+ oclif plugin that implements heroku devcenter:open|pull|push|preview using TypeScript, HTTP calls to Dev Center, local markdown/YAML handling, ~/.netrc auth, and a local preview server.

• Removes the Ruby CLI, gem layout, and bin/devcenter.
• Adds src/ → dist/ build, ESLint (oclif config), CI (multi-OS/Node), Dependabot, components inventory, and updated README/CONTRIBUTING.
• Aligns .c8rc.json and c8 --all --check-coverage with heroku/cli (80% gates on src/**/*.ts).
• Adds a runCommand helper, plus nock/supertest/unit tests.
• Uses DEVCENTER_CLI_CWD / DEVCENTER_CLI_TEST (and DEVCENTER_CLI_TEST_CONFIRM for pull) so tests stay isolated and non-interactive.
• Drafts / private API: pull (and related client changes) now use a private API fallback leveraged by push for draft access

Breaking change: users must switch from the gem/devcenter binary to heroku devcenter:* via the npm plugin.

Type of Change

Breaking Changes (major semver update)

• Add a ! after your change type to denote a change that breaks current behavior

Feature Additions (minor semver update)

• feat: Introduces a new feature to the codebase

Patch Updates (patch semver update)

• fix: Bug fix
• deps: Dependency upgrade
• revert: Revert a previous commit
• chore: Change that does not affect production code
• refactor: Refactoring existing code without changing behavior
• test: Add/update/remove tests

Testing

setup

npm install
npm run build
heroku plugins:link .

First heroku login. Then run help commands

heroku devcenter --help
heroku devcenter:open --help

this will open the page in your browser

heroku devcenter:open error-pages

these should create the .md files in the location you run from and open the preview locally

heroku devcenter:pull slowdb
heroku devcenter:pull https://devcenter.heroku.com/articles/slowdb
heroku devcenter:preview slowdb

This will send an update to the article, not publish if in drafts.

heroku devcenter:push slowdb

Screenshots (if applicable)

Related Issues

GUS work item: W-20867948