Add rails-stats command line executable

[etagwerker]

• Add an entry to CHANGELOG.md that links to this PR under the "main (unreleased)" heading.

Description:

This adds a standalone rails-stats executable so the tool can be run against a directory without having to set up a Rakefile first.

Before, running against an arbitrary directory required a Rakefile and the rake stats[/path/to/app/] invocation. Now you can just call:

$ rails-stats /path/to/app   # absolute path
$ rails-stats path/to/app    # relative path
$ rails-stats                # defaults to the current directory
$ rails-stats path/to/app json  # JSON output

The executable resolves the path with File.absolute_path, so both absolute and relative paths work, prints the resolved directory, and exits with a friendly error (exit code 1) when the directory does not exist. It calls RailsStats::CodeStatistics directly instead of going through Rake.

The gemspec already ships anything under bin/ as an executable (spec.executables = spec.files.grep(%r{^bin/})), so no gemspec change was needed.

README gains a "Run it as a command line tool" section documenting the usage.

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🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR introduces a standalone rails-stats command-line executable so RailsStats can be run against any directory without needing a local Rakefile, and updates documentation/changelog accordingly.

Changes:

• Add bin/rails-stats CLI entrypoint that resolves a target directory and runs RailsStats::CodeStatistics directly.
• Update README usage examples to document the CLI and replace some rake stats[...] examples with rails-stats ....
• Update gemspec executable metadata and add a changelog entry linking to this PR.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 3 comments.

File	Description
README.md	Documents the new CLI usage and updates examples to prefer rails-stats.
rails_stats.gemspec	Updates gem metadata and sets executable/bindir configuration for the new CLI.
CHANGELOG.md	Adds an unreleased feature entry linking to PR #49.
bin/rails-stats	New standalone CLI wrapper around RailsStats::CodeStatistics.

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