debug: Add file checks before build

Dockerfile

@@ -46,6 +46,12 @@ RUN set -e; \
     cp -a src/content/assets/data/. public/data/
 
 # Build the application
+RUN echo "🔍 Debug: Checking if article.mdx exists..." && \
+    ls -lh src/content/article.mdx && \
+    echo "🔍 Debug: Checking if Figure component exists..." && \
+    ls -lh src/components/Figure.astro && \
+    echo "🔍 Debug: First 20 lines of article.mdx:" && \
+    head -20 src/content/article.mdx
 RUN npm run build
 
 # Generate the PDF (light theme, full wait)