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/hymn-intro-e-esus4-e-esus4-e.tex

@@ -48,4 +48,6 @@ to fly you know you might not come down. \\
 Don't try to fly, dear God, you might not come down.
 \end{verse}
 
+\songimage{images/img-128.jpg}
+
 \end{song}