Initial commit: organize Primary song slides repo

One folder per song under songs/. Tracks PPTX slide files and
Python generation scripts. PDFs and videos excluded (too large
for git; originals are in Google Drive).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,6 @@
+# Large binary files — store in Google Drive, not git
+*.mp4
+*.mov
+*.avi
+*.mkv
+*.pdf