feat: add official Codex skill and harden task execution

Install and update artemis-use with task diagnostics and plugin guidance. Preserve cross-device file receipts, review canonical reports, guard stage transitions and reduce small history summaries. Improve exploration lifecycle, request recovery and browser live connections.

tests/conftest.py

@@ -84,3 +84,9 @@ def pytest_collection_modifyitems(items: list[pytest.Item]) -> None:
             item.add_marker(pytest.mark.integration)
         if "e2e" in parts:
             item.add_marker(pytest.mark.e2e)
+
+
+@pytest.fixture(autouse=True)
+def no_host_codex_startup_sync(monkeypatch):
+    """Starting an isolated test app must never modify the real Codex profile."""
+    monkeypatch.setenv("ARTEMIS_SKIP_CODEX_SYNC", "1")