Implement rp CLI: rich-print markdown, JSON, code, and more

- Add typer CLI with auto file-type detection by extension
- Support markdown (rich.Markdown), JSON (rich.JSON), and 30+ code
  languages via Pygments syntax highlighting
- Features: line numbers toggle, pager support, stdin input,
  configurable color themes
- Project metadata: MIT license, author, classifiers, entry point

src/rp/__init__.py

@@ -1,2 +1,4 @@
-def hello() -> str:
-    return "Hello from rp!"
+"""rp — Rich print files beautifully in your terminal."""
+
+__version__ = "0.1.0"
+__author__ = "Yunxiao Xu"