Add RSpec testing infrastructure and GitHub Actions CI

[CJGlitter]

Summary

• Added comprehensive RSpec test suite (9 tests, 100% passing)
• Configured GitHub Actions CI with parallel matrix builds for Ruby 3.0-3.4
• Set up Bundler with development dependencies
• Updated documentation with testing instructions

Changes

Added

• spec/typewrite_spec.rb - Test suite covering output and timing behavior
• spec/spec_helper.rb - RSpec configuration
• .rspec - Default RSpec options (documentation format, color)
• Gemfile - Development dependencies (rspec ~> 3.12, rake ~> 13.0)
• Rakefile - Default task for running tests
• .github/workflows/ci.yml - Parallel CI for Ruby 3.0, 3.1, 3.2, 3.3, 3.4

Updated

• README.md - Added Development section with test instructions

Test Coverage

The test suite verifies:

• Basic output with default parameters
• Custom type_rate and punc_rate parameters
• Line break behavior (true/false)
• Punctuation pauses (., ?, !)
• Edge cases (empty string, single character)

Manual Testing

bundle install
bundle exec rspec       # Run tests directly
bundle exec rake        # Run tests via rake

All 9 tests pass across Ruby 3.0-3.4.

CI Behavior

GitHub Actions will now:

• Run on all PRs and pushes to main
• Test against Ruby 3.0, 3.1, 3.2, 3.3, 3.4 in parallel
• Fail builds if any tests don't pass
• Cache gems for faster subsequent runs