testament-burn: Enhanced build system with HTML output, weasyprint PDF fallback, and print CSS

- build.py: Added weasyprint fallback for PDF when xelatex unavailable
- build.py: Added --html flag for standalone pandoc HTML book output
- book-style.css: Added @media print rules for browser Print-to-PDF
- Makefile: Added 'html' target and weasyprint check to 'make check'
- website/index.html: Added HTML download link and Print to PDF option
- Regenerated testament-complete.md, testament.epub, testament.html

website/index.html

@@ -361,10 +361,11 @@
   <div style="display: flex; flex-wrap: wrap; gap: 1rem; margin: 2rem 0; justify-content: center;">
     <a href="reader.html" class="cta">READ ONLINE</a>
     <a href="https://forge.alexanderwhitestone.com/Timmy_Foundation/the-testament/raw/branch/main/build/output/the-testament.epub" class="cta" style="background: transparent; border: 1px solid var(--green); color: var(--green);">DOWNLOAD EPUB</a>
+    <a href="https://forge.alexanderwhitestone.com/Timmy_Foundation/the-testament/raw/branch/main/testament.html" class="cta" style="background: transparent; border: 1px solid var(--green); color: var(--green);">DOWNLOAD HTML</a>
   </div>
 
   <p style="text-align: center; color: var(--grey); font-size: 0.9rem; margin-top: 1rem;">
-    Formats: HTML reader &middot; EPUB &middot; <a href="https://forge.alexanderwhitestone.com/Timmy_Foundation/the-testament" style="color: var(--green);">Source code</a>
+    Formats: Web reader &middot; EPUB &middot; Standalone HTML &middot; Print to PDF from HTML &middot; <a href="https://forge.alexanderwhitestone.com/Timmy_Foundation/the-testament" style="color: var(--green);">Source code</a>
   </p>
 </section>