Extract and insert 97 images from reference PDF into songs

Extract images from the CL6 PDF using pdfimages, map them to songs
via page-to-CL number matching, and insert \songimage commands.
Add insert-images.py script for repeatable extraction.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

songs/ich-moecht-mit-einem-zirkus-ziehn.tex

@@ -40,4 +40,6 @@ Wagen,/: die meine Welt und deine Welt auf Rädern \\
 heimwärts tragen. :/
 \end{verse}
 
+\songimage{images/img-078.png}
+
 \end{song}