feat: add MCP server core, stdio and streamable HTTP transports and serve command

Low-level SDK server built from the catalog plus gitea_api_request, with TOOLSETS/READ_ONLY/DISABLED_TOOLS filters, schema validation without value echo, one audit event per call, static bearer verifier, identity resolver hook, /health, DNS-rebinding protection, rate limiting and fail-closed startup checks.

tests/test_cli.py

@@ -8,6 +8,7 @@ import pytest
 
 from aegis_gitea_mcp import __version__
 from aegis_gitea_mcp.cli import build_parser, main
+from tests.test_server_helpers import ANY_HOST
 
 
 def test_version_prints_package_version(capsys: pytest.CaptureFixture[str]) -> None:
@@ -15,12 +16,9 @@ def test_version_prints_package_version(capsys: pytest.CaptureFixture[str]) -> N
     assert capsys.readouterr().out.strip() == __version__
 
 
-@pytest.mark.parametrize("argv", [[], ["serve"], ["serve", "--transport", "http"]])
-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_parses_host_and_port() -> None:
+    args = build_parser().parse_args(["serve", "--host", ANY_HOST, "--port", "9000"])
+    assert (args.host, args.port) == (ANY_HOST, 9000)
 
 
 def test_serve_transport_choices() -> None: