fix: resolve CI failures — ESLint unused vars and AI chat tests in CI

Frontend: suppress unused-vars ESLint errors for callback params in
MaintenanceFlowDetailPage and StepLibraryPage.

Backend: add autouse fixture to mock settings.ai_enabled=True in
test_ai_chat.py so tests pass in CI where no ANTHROPIC_API_KEY is set.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/tests/test_ai_chat.py

@@ -3,11 +3,22 @@
 These tests mock the AI provider to avoid real API calls.
 """
 import pytest
-from unittest.mock import AsyncMock, patch
+from unittest.mock import AsyncMock, patch, PropertyMock
 
 pytestmark = pytest.mark.asyncio
 
 
+@pytest.fixture(autouse=True)
+def _enable_ai():
+    """Ensure ai_enabled returns True even without API keys in CI."""
+    with patch(
+        "app.core.config.Settings.ai_enabled",
+        new_callable=PropertyMock,
+        return_value=True,
+    ):
+        yield
+
+
 @pytest.fixture
 def mock_ai_provider():
     """Mock AI provider that returns realistic responses."""