Remove redundant docx/pdf exports, add .gitignore

The .md files are the source of truth; the accompanying .docx/.pdf
exports for every doc just doubled the repo size and would drift out
of sync as soon as the markdown changed. Also dropped the empty,
unreferenced scripts/ directory.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,8 @@
+# Exported copies of markdown docs — the .md file is the source of truth
+*.docx
+*.pdf
+
+# OS / editor cruft
+.DS_Store
+Thumbs.db
+*.swp