testament-burn: Build browser-based 'The Door' text adventure (HTML/JS)

- Complete interactive text adventure playable in any browser
- All rooms from Python game: Bridge, Hard Room, Record, Wall, Timmy talk
- Slow-print narration, ambient atmosphere, trust system
- Multiple endings based on choices (stayed, spoke, signed wall)
- Crisis resources at ending
- Added 'PLAY IN BROWSER' button to landing page
- ~36KB self-contained HTML file, no dependencies

website/index.html

@@ -396,6 +396,7 @@
   </div>
 
   <p style="text-align: center; margin-top: 1.5rem;">
+    <a href="the-door.html" class="cta">PLAY IN BROWSER</a>
     <a href="https://forge.alexanderwhitestone.com/Timmy_Foundation/the-testament/raw/branch/main/game/the-door.py" class="cta" style="background: transparent; border: 1px solid var(--green); color: var(--green);">DOWNLOAD THE GAME</a>
   </p>
 </section>