test(api): gated live Ollama smoke (--run-live) + env docs

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

api/conftest.py

@@ -0,0 +1,21 @@
+"""Gate `@pytest.mark.live` tests (they hit a real Ollama) behind --run-live so
+the default suite stays hermetic. Run the live layer with: pytest --run-live
+"""
+
+import pytest
+
+
+def pytest_addoption(parser):
+    parser.addoption(
+        "--run-live", action="store_true", default=False,
+        help="run tests marked @pytest.mark.live (require a real Ollama)",
+    )
+
+
+def pytest_collection_modifyitems(config, items):
+    if config.getoption("--run-live"):
+        return
+    skip_live = pytest.mark.skip(reason="needs --run-live (real Ollama)")
+    for item in items:
+        if "live" in item.keywords:
+            item.add_marker(skip_live)