Scaffold hello-world apps, test frameworks, and Gitea CI

- uv workspace tying nisse-core, nisse-dev, nisse-ops together
  (src layouts, workspace-sourced nisse-core dependency)
- Placeholder hello-world entry points for both agents, calling
  through nisse-core to exercise the package boundary
- pytest unit tests per package; integration tests (marker-gated)
  running the installed console scripts as subprocesses
- ruff lint + format, nisse_* declared first-party
- Gitea Actions workflow running lint, format check, unit and
  integration tests; scripts/check.sh mirrors it locally

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

pyproject.toml

@@ -0,0 +1,29 @@
+[tool.uv.workspace]
+members = ["nisse-core", "nisse-dev", "nisse-ops"]
+
+[dependency-groups]
+dev = [
+    "pytest>=8",
+    "ruff>=0.6",
+]
+
+[tool.pytest.ini_options]
+testpaths = [
+    "nisse-core/tests",
+    "nisse-dev/tests",
+    "nisse-ops/tests",
+    "tests",
+]
+addopts = "--strict-markers"
+markers = [
+    "integration: end-to-end tests that exercise installed entry points or external services",
+]
+
+[tool.ruff]
+target-version = "py312"
+
+[tool.ruff.lint]
+extend-select = ["I"]
+
+[tool.ruff.lint.isort]
+known-first-party = ["nisse_core", "nisse_dev", "nisse_ops"]