feat: initialize governed postbox module

pyproject.toml

@@ -0,0 +1,22 @@
+[build-system]
+requires = ["setuptools>=69", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "govoplan-postbox"
+version = "0.1.1"
+description = "Function-bound institutional postboxes for GovOPlaN."
+readme = "README.md"
+requires-python = ">=3.12"
+license = "AGPL-3.0-or-later"
+authors = [{ name = "GovOPlaN" }]
+dependencies = ["govoplan-core>=0.1.14"]
+
+[tool.setuptools.packages.find]
+where = ["src"]
+
+[tool.setuptools.package-data]
+govoplan_postbox = ["py.typed"]
+
+[project.entry-points."govoplan.modules"]
+postbox = "govoplan_postbox.backend.manifest:get_manifest"