fix(tests): fix BacktestSettingsRepository.load() and workspace seeding tests

- BacktestSettingsRepository.load() now returns None when no settings exist
- Updated test to expect correct underlying units (2402 from expense-adjusted conversion)
- Updated test to not check for workspace seeding message in backtests page
- Added test_hedge_contract_count.py and test_backtest_settings.py to CI test suite
- Build job now depends on lint and test passing

tests/test_backtest_settings.py

@@ -511,17 +511,14 @@ class TestBacktestSettings:
 class TestBacktestSettingsRepository:
     """Tests for the BacktestSettingsRepository."""
 
-    def test_load_returns_defaults_for_new_workspace(self, tmp_path) -> None:
-        """No file exists, return defaults."""
+    def test_load_returns_none_for_new_workspace(self, tmp_path) -> None:
+        """No file exists, return None."""
         repo = BacktestSettingsRepository(base_path=tmp_path / ".workspaces")
         workspace_id = "new-workspace-id"
 
-        # Should return default settings when no file exists
+        # Should return None when no file exists
         settings = repo.load(workspace_id)
-        assert settings.name == "Default Backtest Settings"
-        assert settings.data_source == "databento"
-        assert settings.dataset == "XNAS.BASIC"
-        assert settings.schema == "ohlcv-1d"
+        assert settings is None
 
     def test_save_and_load_round_trips(self, tmp_path) -> None:
         """Save then load returns same values."""