feat!: Core Architecture and CLI Redesign

[sauce-base]

This pull request is a major refactor that transitions saucebase/installer from a Laravel package to a standalone, globally-installed Composer CLI tool, similar to laravel/installer. The CLI now exposes saucebase new, saucebase install, and saucebase stack commands, and no longer relies on Laravel's package discovery or service providers. The documentation and architecture have been thoroughly rewritten to reflect this new model, and the codebase and Composer configuration have been updated accordingly.

Key changes include:

Core Architecture and CLI Redesign

• Refactored saucebase/installer to be a standalone, globally-installed Composer CLI tool (not a Laravel package), with a saucebase binary exposing new, install, and stack commands. The CLI operates on external target directories and no longer uses service providers or package discovery. (CLAUDE.md [1] [2]; README.md [3]
• Updated the architecture to use a minimal Illuminate\Console\Application, registering commands via a custom container, and running all artisan steps as subprocesses in the target directory. (CLAUDE.md CLAUDE.mdR28-R90)
• Updated composer.json to add the bin/saucebase binary, remove the extra.laravel.providers section, and add new dependencies required for standalone operation (composer-runtime-api, guzzlehttp/guzzle, illuminate/container, illuminate/events, laravel/installer). (composer.json [1] [2]

Command and Flow Changes

• saucebase new <name> scaffolds a new project via laravel/installer and runs the full install flow, collecting all prompts upfront for unattended installation. (README.md [1]; CLAUDE.md [2]
• saucebase install provisions an existing app directory, supporting both Docker and native drivers with improved flow and options. (README.md README.mdL5-R113)
• saucebase stack <vue|react> switches the frontend framework, now operating on a target path and supporting dev/contributor mode. (README.md [1]; CLAUDE.md [2]
• Docker and native flows have been rewritten to copy Docker stubs directly, run all commands in the correct context, and handle SSL, environment, and module setup more robustly. (CLAUDE.md CLAUDE.mdR28-R90)

Documentation and Testing

• Rewrote README.md and CLAUDE.md to document the new CLI interface, installation, requirements, and architecture, removing all references to the old Laravel package model. (README.md [1]; CLAUDE.md [2] [3]
• Updated testing strategy to plain PHPUnit (no Testbench, no Laravel app), reflecting the new standalone CLI approach. (CLAUDE.md CLAUDE.mdR28-R90)

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These changes make saucebase/installer a modern, first-class CLI for Saucebase apps, decoupled from the Laravel package ecosystem and ready for global Composer installation.