feat(cli): add open-reuse validate and register portfolio integrations

Implement Integration Definition validator CLI with schema and index checks,
pytest suite, and CI workflow. Register open-cmis-tck and issue-core-gitea in
the integration index.

Closes OPEN-WP-0003 and OPEN-WP-0004.

pyproject.toml

@@ -0,0 +1,26 @@
+[build-system]
+requires = ["setuptools>=68"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "open-reuse"
+version = "0.1.0"
+description = "Integration registry tooling for open-reuse"
+readme = "README.md"
+requires-python = ">=3.11"
+dependencies = [
+  "jsonschema>=4.0",
+  "pyyaml>=6.0",
+]
+
+[project.optional-dependencies]
+dev = [
+  "pytest>=8.0",
+]
+
+[project.scripts]
+open-reuse = "open_reuse.cli:main"
+
+[tool.setuptools.packages.find]
+where = ["."]
+include = ["open_reuse*"]