Add Spanish language support to book build

[khaos-codi]

Add Spanish Language Support to Book Build

This PR enables building and publishing Spanish language versions of "Actual Intelligence" by:

1. Adding Spanish to supported languages in tools/build.js
2. Adding Spanish localization for titles and metadata
3. Setting up Spanish output files with proper names ("inteligencia-real.*")
4. Creating language-specific directories in build folder
5. Implementing multi-language build support with command line flags:
   • --all-languages: Build all supported languages
   • --lang=es: Build only the Spanish version
   • Default: Build only English version

Key Improvements:

• Language-specific metadata: Spanish books get the proper title "Inteligencia Real" and subtitle in Spanish
• Language-specific output directories: Spanish files are placed in /es/ subdirectory in build/
• Multiple output formats: Generates PDF, EPUB, MOBI, and HTML for each language
• Copy to root folder for release: Language-specific files are copied to root build folder for GitHub Releases
• Index files for GitHub Pages: Generates appropriate index.html files for both languages

How to Test:

• Run npm run build to build the English book (default)
• Run npm run build -- --all-languages to build both English and Spanish
• Run npm run build -- --lang=es to build only the Spanish version
• Check the build directory to see the language-specific files and structure

I've preserved all the existing functionality while adding support for the Spanish language. This makes it easy to add more languages in the future.