fix: add build-system and remove conflicting license classifier

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

Author: xfgong

pyproject.toml

@@ -9,7 +9,6 @@ classifiers = [
     "Development Status :: 3 - Alpha",
     "Framework :: AsyncIO",
     "Intended Audience :: Developers",
-    "License :: OSI Approved :: MIT License",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
@@ -38,5 +37,9 @@ dev = [
 asyncio_mode = "auto"
 testpaths = ["tests"]
 
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
 [tool.hatch.build.targets.wheel]
 packages = ["cubepi"]