Rewrite as a Rails-free Webpack 5 CLI (1.0.0)

[danielpclark]

Summary

Webpacker is abandoned, and 0.x depended on it via a mocked Rails app. This rewrite removes that layer and drives Webpack 5 directly.

• No runtime gem dependencies (removed webpacker, tty-command, bundler, and the Rails mock).
• init generates config/webpacker.yml, an editable config/webpack/webpack.config.js, an entry pack, and a package.json with tooling pinned by major version (webpack ^5, webpack-cli ^6, etc.). Existing files are kept unless --force.
• Commands: init, compile, watch, clobber, check, info, version.
• Keeps Webpacker's conventions: webpacker.yml keys, app/javascript/packs entries, hashed output and a flat public/packs/manifest.json.
• Environment is read from WEBPACKER_ENV, NODE_ENV or RAILS_ENV (default development, as Webpacker did).
• Replaced Travis with GitHub Actions; rewrote README (includes a 0.x migration note).

Breaking changes

• webpacker:* rake tasks, Gemfile, Rakefile, bin/rails, config/application.rb and config/webpack/loaders are no longer generated; custom loaders move into webpack.config.js.
• Requires Ruby >= 3.0 and Node >= 20.9.

Test plan

• Unit tests pass via ruby -Ilib -Itest (7 runs, 1 skipped)
• End-to-end test (WEBPACKER_CLI_E2E=1): real init + production compile, manifest verified
• Manual: CSS + SVG asset build, check, info, clobber
• rake test and the new GitHub Actions workflow have not been run (rake unavailable in the dev container)

🤖 Generated with Claude Code

https://claude.ai/code/session_01LaJESXoiQCpeTydMCJ37uU

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Changed Files

File	Status
.github/workflows/ci.yml	0% smaller
.travis.yml	0% smaller
Gemfile	Unsupported file format
README.md	Unsupported file format
bin/webpacker-cli	Unsupported file format
lib/webpacker_cli.rb	Unsupported file format
lib/webpacker_cli/rails_template.rb	Unsupported file format
lib/webpacker_cli/templates/application.js	0% smaller
lib/webpacker_cli/templates/package.json	0% smaller
lib/webpacker_cli/templates/webpack.config.js	0% smaller
lib/webpacker_cli/templates/webpacker.yml	0% smaller
lib/webpacker_cli/version.rb	Unsupported file format
test/test_helper.rb	Unsupported file format
test/webpacker_cli_test.rb	Unsupported file format
webpacker_cli.gemspec	Unsupported file format