Add commander dependency and CLI flag support

[Josephat-S]

This pull request introduces a major refactor to the CLI in index.js, migrating from a purely interactive prompt-based approach to a robust command-line interface using the commander library. It adds support for command-line flags, improves input validation, and allows both interactive and non-interactive (flag-driven) project scaffolding. Additionally, it introduces several quality-of-life improvements such as skipping dependency installation with a flag and dynamically displaying the current version from package.json.

The most important changes are:

CLI Architecture & Command Handling:

• Refactored the CLI to use the commander library, supporting subcommands and options for non-interactive usage, and providing a more standard CLI experience. The default behavior now routes to the create command, and help/version info is available. (index.js) [1] [2] [3]

Flag and Argument Support:

• Added support for command-line flags for template, architecture, design, variant, navigation count, sidebar, git initialization, dependency installation, and a --yes shortcut for all defaults. Includes input validation and graceful error messaging for invalid options. (index.js) [1] [2] [3]

Interactive Prompt Improvements:

• Prompts are now dynamically built, skipping questions for any options already provided via flags. The prompt flow is cleaner, and merging of flag and prompt results is handled systematically. (index.js) [1] [2]

Version Handling and UX:

• The CLI banner now dynamically displays the version from package.json instead of a hardcoded value, improving maintainability and user awareness. (index.js)

Project Generation Enhancements:

• Added a --no-install flag to skip dependency installation, with corresponding logic in the project generation flow and user feedback. (src/generate.js) [1] [2]

Closes #39