Fix Spanish book generation in Docker container build

[khaos-codi]

Multilingual Support Enhancement

This PR fixes the issue where Spanish versions of the book were not being generated correctly in the Docker container build.

Root Causes Identified:

1. Resource Path Issues: The Spanish resource paths weren't consistently handled across all conversion tools
2. File Copying Logic: The file copying in the build script wasn't explicit enough about maintaining Spanish files in root build directory
3. Language-specific Metadata: Missing explicit language tags in some conversion steps
4. Build Directory Structure: Inconsistent directory creation for Spanish files

Changes Made:

1. Enhanced generate-epub.sh Script

   • Added better language-specific resource path handling
   • Improved language-specific cover image detection
   • Added proper metadata language tag to all conversion steps
   • Reduced file size threshold for warnings to be more accurate

2. Improved build-language.sh Script

   • Added more explicit file copying for non-English languages to root build directory
   • Enhanced error handling and verification when files are missing
   • Added detailed logging for better debugging
   • Made resource paths more consistent across languages

3. Upgraded copy-images.sh Script

   • Enhanced directory structure to ensure Spanish images are copied properly
   • Added verbose logging for image copying operations
   • Implemented better verification of image copies
   • Special handling for cover image to ensure availability in all language directories

4. Enhanced setup.sh Script

   • Added locale handling for better international character support
   • Added a Spanish README template to ensure es directory exists
   • Improved directory creation process for language-specific folders
   • Added better reporting of build environment status

5. Updated GitHub Workflow

   • Added explicit verification steps for Spanish files
   • Added fallback copy operations if files are found in language subdirectories but not in root
   • Enhanced the cover image handling in the setup phase
   • Added detailed file size reporting for debugging

Testing:

I've made sure that:

1. All these changes preserve the existing English book generation that's working
2. The Spanish book files are correctly identified and included in the release process
3. Images are properly handled for both languages
4. Necessary directories are created early in the process

This should resolve issue #46 and allow for both English and Spanish books to be released together.

Fixes #46