[FIX] gitignore: .DS_Store too — the first version was half a job

I wrote the ignore file for __pycache__, declared the tree clean, and .DS_Store
appeared in the same breath. Same class of machine droppings, same one-line fix;
listing one and not the other just means the next status is dirty again.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WuMjg3ipEVa3n8CoSzoyvc

.gitignore

@@ -1,3 +1,6 @@
 # Generated by the governance MCP server importing wake-digest.py on every launch
 __pycache__/
 *.pyc
+
+# macOS Finder droppings
+.DS_Store