feat: add backtesting functionality with UI and API endpoints

- Introduced backtesting page and fragment in the dashboard for running backtests and viewing recent reports.
- Implemented backtest run logic with configuration options including event path, starting balances, trade capital, and fee profiles.
- Added recent backtest reports storage and retrieval.
- Created a new strategy module for statistical arbitrage experiments with validation on configuration parameters.
- Updated settings to include parameters for the statistical arbitrage strategy.
- Enhanced dashboard controls to support the new strategy mode.
- Added unit tests for backtesting functionality and strategy validation.
- Updated templates for backtesting UI integration.

tests/unit/test_settings_validation.py

@@ -53,3 +53,20 @@ def test_valid_security_configuration_passes() -> None:
     )
 
     assert settings.kraken_api_key_permissions == "query,trade"
+
+
+def test_stat_arb_entry_zscore_must_exceed_exit_zscore() -> None:
+    with pytest.raises(ValidationError):
+        Settings(
+            _env_file=None,
+            STRATEGY_STAT_ARB_ENTRY_ZSCORE="0.5",
+            STRATEGY_STAT_ARB_EXIT_ZSCORE="0.5",
+        )
+
+
+def test_stat_arb_lookback_window_must_be_at_least_two() -> None:
+    with pytest.raises(ValidationError):
+        Settings(
+            _env_file=None,
+            STRATEGY_STAT_ARB_LOOKBACK_WINDOW="1",
+        )