feat: add pneumatube gateway bridging smolmail and SMTP via LMTP

pyproject.toml

@@ -0,0 +1,26 @@
+[project]
+name = "pneumatube"
+version = "0.1.0"
+description = "Gateway bridging a smolmail account and an SMTP mailbox"
+requires-python = ">=3.11"
+dependencies = [
+    "pynacl>=1.5",
+    "noiseprotocol>=0.3.1",
+    "aiosmtpd>=1.4",
+]
+
+[project.scripts]
+pneumatube = "pneumatube.__main__:main"
+
+[dependency-groups]
+dev = ["pytest>=8.0"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+
+[build-system]
+requires = ["setuptools>=68", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[tool.setuptools.packages.find]
+where = ["src"]