feat(audit): record user_id on log events

backend/tests/test_audit_log_user_id.py

@@ -0,0 +1,61 @@
+"""Audit log entries record the acting user_id.
+
+Schema: the ``audit_log`` table has a ``user_id INTEGER`` column added
+by migration 0011; the SQLAlchemy ``AuditLog`` model itself does not
+declare it yet, so ``append_event`` cannot pass it through. These tests
+fail before the model + dataclass are updated, and pass after.
+"""
+
+from __future__ import annotations
+
+import pytest
+from sqlalchemy import delete, select
+
+from cyclone.audit_log import AuditEvent, append_event
+from cyclone.db import AuditLog, SessionLocal, User
+
+
+@pytest.fixture(autouse=True)
+def _clear():
+    with SessionLocal()() as db:
+        db.execute(delete(AuditLog))
+        db.execute(delete(User))
+        db.commit()
+    yield
+    with SessionLocal()() as db:
+        db.execute(delete(AuditLog))
+        db.execute(delete(User))
+        db.commit()
+
+
+def test_append_event_accepts_user_id_kwarg():
+    with SessionLocal()() as db:
+        append_event(
+            db,
+            AuditEvent(
+                event_type="test",
+                entity_type="x",
+                entity_id="y",
+                user_id=42,
+            ),
+        )
+        db.commit()
+    with SessionLocal()() as db:
+        row = db.execute(select(AuditLog)).scalars().one()
+    assert row.user_id == 42
+
+
+def test_append_event_without_user_id_is_null():
+    with SessionLocal()() as db:
+        append_event(
+            db,
+            AuditEvent(
+                event_type="test",
+                entity_type="x",
+                entity_id="y",
+            ),
+        )
+        db.commit()
+    with SessionLocal()() as db:
+        row = db.execute(select(AuditLog)).scalars().one()
+    assert row.user_id is None