docs: rewrite README with quick start, features, and usage guide; migrate setup.py to pyproject.toml with improved metadata

Author: erinshek

.gitignore

@@ -158,3 +158,6 @@ cython_debug/
 #  and can be added to the global gitignore or merged into this file.  For a more nuclear
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
 .idea/
+
+# Claude Code
+CLAUDE.md