test: integration coverage report, suite docs and harness isolation fix

tests/integration/test_harness.py

@@ -127,7 +127,10 @@ def test_cleanup_removes_container_and_network() -> None:
     assert run_id not in harness._ACTIVE
 
 
-def test_cleanup_all_handles_registered_runs() -> None:
+def test_cleanup_all_handles_registered_runs(monkeypatch: pytest.MonkeyPatch) -> None:
+    # cleanup_all removes every tracked run, including the session's own Gitea, so this
+    # test works on a private registry instead of the real one.
+    monkeypatch.setattr(harness, "_ACTIVE", {})
     run_id = harness.secrets.token_hex(4)
     name = f"{harness.NAME_PREFIX}{run_id}"
     harness.register_resources(RunResources(run_id=run_id, container=name, network=name))