README: add status badges (License, PyPI, Python, CI, Rust core)

Python analogs of jRegTab's shields: MIT license, PyPI version (replaces
Maven Central), Python 3.10+ (replaces Java 21+), GitHub Actions CI status,
and a Rust-core badge for the hybrid Python/Rust build.

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

Author: shigarov

README.md

@@ -1,5 +1,11 @@
 # pyRegTab
 
+[![License: MIT](https://img.shields.io/badge/License-MIT-green.svg)](https://opensource.org/licenses/MIT)
+[![PyPI](https://img.shields.io/pypi/v/pyregtab.svg)](https://pypi.org/project/pyregtab/)
+[![Python](https://img.shields.io/badge/Python-3.10%2B-blue.svg)](https://www.python.org/)
+[![CI](https://github.com/regtab/pyregtab/actions/workflows/ci.yml/badge.svg)](https://github.com/regtab/pyregtab/actions/workflows/ci.yml)
+[![Rust core](https://img.shields.io/badge/core-Rust-orange.svg)](https://www.rust-lang.org/)
+
 RegTab: pattern-driven data extraction from document tables with regular
 structure — the Python port of jRegTab with a native Rust core.