Switch to pyproject.toml and add matplotlib dependency

- Remove setup.py in favor of pyproject.toml build system
- Add matplotlib to dev dependencies in pyproject.toml
- Alphabetize dev dependencies list for better maintainability

Resolves conflicts with master branch build system changes.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: vahid-ahmadi

pyproject.toml

@@ -0,0 +1,76 @@
+[project] 
+name = "policyengine-uk"
+version = "2.39.3"
+description = "PolicyEngine tax and benefit system for the UK"
+readme = "README.md"
+authors = [
+    { name = "PolicyEngine", email = "nikhil@policyengine.org" }
+]
+maintainers = [
+    { name = "Nikhil Woodruff", email = "nikhil.woodruff@outlook.com" }
+]
+license = { text = "AGPL-3.0" }
+keywords = ["benefit", "microsimulation", "social", "tax"]
+classifiers = [
+    "Development Status :: 5 - Production/Stable",
+    "License :: OSI Approved :: GNU Affero General Public License v3",
+    "Operating System :: POSIX",
+    "Programming Language :: Python",
+    "Topic :: Scientific/Engineering :: Information Analysis",
+]
+requires-python = ">=3.10"
+dependencies = [
+    "policyengine-core>=3.6.4",
+    "microdf-python",
+]
+
+[project.urls]
+Homepage = "https://github.com/PolicyEngine/policyengine-uk"
+Repository = "https://github.com/PolicyEngine/policyengine-uk"
+
+[project.scripts]
+# Add console scripts here if needed
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build]
+include = [
+    "policyengine_uk/**/*",
+    "CHANGELOG.md",
+    "LICENSE",
+    "README.md",
+]
+
+[tool.hatch.build.targets.wheel]
+packages = ["policyengine_uk"]
+
+[tool.hatch.build.targets.wheel.shared-data]
+"CHANGELOG.md" = "share/openfisca/openfisca-country-template/CHANGELOG.md"
+"LICENSE" = "share/openfisca/openfisca-country-template/LICENSE"
+"README.md" = "share/openfisca/openfisca-country-template/README.md"
+
+[dependency-groups]
+dev = [
+    "tables>=3.10.1",
+]
+
+[project.optional-dependencies]
+dev = [
+    "black",
+    "coverage",
+    "furo<2023",
+    "jupyter-book",
+    "linecheck",
+    "matplotlib",
+    "pytest",
+    "pytest-cov",
+    "setuptools",
+    "snowballstemmer>=2,<3",
+    "sphinx-argparse>=0.3.2,<1",
+    "sphinx-math-dollar>=1.2.1,<2",
+    "tqdm",
+    "wheel",
+    "yaml-changelog>=0.1.7",
+]