fix(mcp): Skip e2e tests in CI unless --run-e2e is passed

E2e tests hit a real external MCP server and are inherently flaky.
Skip them by default, require --run-e2e flag to opt in.

autogpt_platform/backend/backend/blocks/mcp/conftest.py

@@ -9,6 +9,27 @@ full SpinTestServer infrastructure.
 import pytest
 
 
+def pytest_configure(config: pytest.Config) -> None:
+    config.addinivalue_line("markers", "e2e: end-to-end tests requiring network")
+
+
+def pytest_collection_modifyitems(
+    config: pytest.Config, items: list[pytest.Item]
+) -> None:
+    """Skip e2e tests unless --run-e2e is passed."""
+    if not config.getoption("--run-e2e", default=False):
+        skip_e2e = pytest.mark.skip(reason="need --run-e2e option to run")
+        for item in items:
+            if "e2e" in item.keywords:
+                item.add_marker(skip_e2e)
+
+
+def pytest_addoption(parser: pytest.Parser) -> None:
+    parser.addoption(
+        "--run-e2e", action="store_true", default=False, help="run e2e tests"
+    )
+
+
 @pytest.fixture(scope="session")
 def server():
     """No-op override — MCP tests don't need the full platform server."""