Add JavaScript Web Project Scaffolding

[kumarswamynaidu09]

Summary

Adds JavaScript web project scaffolding to Spawn as a new web-js template.

The new template supports four project types:

• Vanilla JavaScript
• Express
• React (Vite)
• Next.js

Framework selection follows the same pattern as the existing Backend API template.

Changes

• Added WebJSTemplate with framework and extras support.

• Added starter files and package.json generation for all four frameworks.

• Registered the new web-js template in registry.py.

• Added optional support for:

  • ESLint
  • Prettier
  • GitHub Actions

• get_dependencies() returns no Python dependencies.

• post_install() automatically runs npm install when Node.js and npm are available.

Fixes

• Fixed CSS template formatting errors caused by unescaped {} characters in style.css, App.css, and globals.css.
• Fixed Windows npm installation failures by passing the resolved npm.cmd path to subprocess.run().
• Added FileNotFoundError handling so npm installation failures do not abort project creation.

Testing

Verified generation for all four supported frameworks.

Tests confirm:

• All starter files generate successfully.
• CSS/JS/JSX templates render without format_map() errors.
• Generated package.json files are valid JSON.
• npm installation behavior works correctly when npm is missing, fails to launch, exits unsuccessfully, or resolves to a platform-specific executable path.

Impact

This expands Spawn's scaffolding capabilities to JavaScript web development while keeping the existing template and CLI architecture unchanged.