docs: Add HTML documentation generator and improve documentation structure

- Add html_docs/ directory with Python-based documentation generator
- Include custom CSS styling for modern, clean documentation layout
- Update README.md with improved formatting and documentation links
- Enhance markdown documentation across all docs/ files:
  - Improve API documentation with better code examples
  - Refactor DOCUMENTATION_INDEX.md for clearer navigation
  - Update EMBEDDING.md, CUSTOMIZATION.md, and other guides
  - Standardize formatting and improve readability throughout
- Fix inconsistent line endings and formatting issues

The HTML documentation generator creates a styled, browsable version
of the project documentation for easier reading and navigation.

docs/SPLASH_SCREENS.md

@@ -21,10 +21,10 @@ Each splash screen:
 
 The logo images are **always embedded** into the executable in both development and release builds. This means:
 
-- ✅ No external logo files needed
-- ✅ Consistent splash screens across all builds
-- ✅ No risk of missing logo files
-- ✅ Clean appearance from the start
+-  No external logo files needed
+-  Consistent splash screens across all builds
+-  No risk of missing logo files
+-  Clean appearance from the start
 
 ### Asset Loading Integration
 
@@ -149,8 +149,7 @@ Here's what a typical game startup looks like with everything enabled:
 ReiLua.exe MyGame/
 ```
 
-**User Experience:**
-
+User Experience:
 1. **Splash Screen 1** (4.1 seconds)
    - Custom text displayed in bold (default: "YOUR STUDIO NAME")
    - Red background (Raylib color #E62937)