feat: new settings, CLI skeleton and interface skeletons

Adds the pydantic-settings Settings with validated GITEA_URL, OAuth scopes
and toolsets, the argparse CLI skeleton, catalog.model, identity and
GiteaAPIError. Test fixtures now isolate env, cwd and state paths in tmp.

tests/test_cli.py

@@ -0,0 +1,37 @@
+"""Tests for the command line skeleton."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+
+from aegis_gitea_mcp import __version__
+from aegis_gitea_mcp.cli import build_parser, main
+
+
+def test_version_prints_package_version(capsys: pytest.CaptureFixture[str]) -> None:
+    assert main(["version"]) == 0
+    assert capsys.readouterr().out.strip() == __version__
+
+
+@pytest.mark.parametrize("argv", [[], ["serve"], ["serve", "--transport", "http"], ["setup"]])
+def test_unbuilt_commands_exit_2(argv: list[str], capsys: pytest.CaptureFixture[str]) -> None:
+    assert main(argv) == 2
+    captured = capsys.readouterr()
+    assert "not implemented yet" in captured.err
+    assert captured.out == ""
+
+
+def test_serve_transport_choices() -> None:
+    parser = build_parser()
+    assert parser.parse_args(["serve", "--transport", "stdio"]).transport == "stdio"
+    with pytest.raises(SystemExit):
+        parser.parse_args(["serve", "--transport", "sse"])
+
+
+def test_package_version_matches_pyproject() -> None:
+    tomllib = pytest.importorskip("tomllib")  # Python 3.11+
+
+    data = tomllib.loads((Path(__file__).parent.parent / "pyproject.toml").read_text())
+    assert data["project"]["version"] == __version__