Add .gitignore for OS and editor cruft

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Kyome22

.gitignore

@@ -0,0 +1,15 @@
+# macOS
+.DS_Store
+
+# Windows
+Thumbs.db
+ehthumbs.db
+
+# Editor / IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+
+# Logs
+*.log