chore: remove sensitive metadata and build artifacts from repo

- Remove .claude/ agent memory (contains personal info)
- Remove build-windows/ CMake artifacts
- Update .gitignore: add build-*, .claude/, dist-windows/, OS files

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

.gitignore

@@ -1,5 +1,7 @@
 # Build
 build/
+build-*/
+dist-windows/
 
 # Output images
 output/
@@ -13,3 +15,13 @@ output/
 *.o
 *.a
 *.so
+*.exe
+
+# Claude Code internal metadata
+.claude/
+
+# OS
+.DS_Store
+Thumbs.db
+*~
+*.swp