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>

nisse-dev/pyproject.toml

@@ -0,0 +1,16 @@
+[project]
+name = "nisse-dev"
+version = "0.1.0"
+description = "Dev agent: plans and implements software projects, produces Gitea PRs"
+requires-python = ">=3.12"
+dependencies = ["nisse-core"]
+
+[project.scripts]
+nisse-dev = "nisse_dev.main:main"
+
+[tool.uv.sources]
+nisse-core = { workspace = true }
+
+[build-system]
+requires = ["uv_build>=0.12,<0.13"]
+build-backend = "uv_build"