[F061] drop type:ignore from audit-emit tests

Convention: no type:ignore/noqa. The F061 in-session audit-emit
tests used '# type: ignore[assignment]' to assign a MagicMock to
AsyncSession.add, and the F060 test assigned to .flush the same way.

Rewritten to hold a local 'session: MagicMock' variable (mypy sees
its auto-children as MagicMock, so .add.side_effect / .flush assign
cleanly with no suppression). Verified via 'mypy tests/' that both
files are now type-clean (the F060/F061 commits had skipped tests/
in mypy, masking two method-assign errors).

tests/unit/services/test_escalation_board_guard.py

@@ -533,9 +533,11 @@ async def test_apply_escalation_emits_blocked_audit_event() -> None:
     The audit row is written into the caller's session (F061/F073/F075: it
     commits atomically with the transition, not fire-and-forget on a separate
     connection), so we assert on the ``AuditLogTable`` added to the session."""
-    svc = _service()
+    session = MagicMock()
+    session.flush = AsyncMock()
     added: list[object] = []
-    svc.session.add = MagicMock(side_effect=added.append)  # type: ignore[assignment]
+    session.add.side_effect = added.append
+    svc = TaskService(session)
     task = MagicMock(
         id=uuid4(),
         parent_task_id=uuid4(),
@@ -573,9 +575,11 @@ async def test_unblock_with_restore_emits_audit_event() -> None:
     The audit row is written into the caller's session (F061/F073/F075: atomic
     with the transition, not fire-and-forget), so we assert on the
     ``AuditLogTable`` added to the session."""
-    svc = _service()
+    session = MagicMock()
+    session.flush = AsyncMock()
     added: list[object] = []
-    svc.session.add = MagicMock(side_effect=added.append)  # type: ignore[assignment]
+    session.add.side_effect = added.append
+    svc = TaskService(session)
     task = MagicMock(
         id=uuid4(),
         status=TaskStatus.BLOCKED,

tests/unit/services/test_task.py

@@ -1076,8 +1076,9 @@ async def test_finalize_claim_rollback_emits_reversal_audit() -> None:
     audit trail diverges from real state and corrupts every downstream metric
     reconstructed from `task.<status>` events (cycle time, bottlenecks).
     """
-    svc = TaskService(MagicMock())
-    svc.session.flush = AsyncMock()
+    session = MagicMock()
+    session.flush = AsyncMock()
+    svc = TaskService(session)
 
     task = _build_task(
         status=TaskStatus.PENDING,
@@ -1134,9 +1135,10 @@ async def test_emit_status_transition_audit_writes_in_session_atomically() -> No
     ``session.add``-ed (same txn) with the metric-reconstruction details, and
     NO fire-and-forget background task is spawned.
     """
-    svc = TaskService(MagicMock())
+    session = MagicMock()
     added: list[object] = []
-    svc.session.add = MagicMock(side_effect=added.append)  # type: ignore[assignment]
+    session.add.side_effect = added.append
+    svc = TaskService(session)
     prior_bg = set(svc._background_tasks)
 
     task = MagicMock(id=uuid4(), claimed_by=uuid4(), team=Team.BACKEND)