fix: update test fixtures for SQLite storage migration

All store tests were passing file paths instead of Database objects
after the JSON-to-SQLite migration. Updated fixtures to create temp
Database instances, rewrote backup e2e tests for binary .db format,
and fixed config tests for the simplified StorageConfig.

server/tests/core/test_automation_engine.py

@@ -25,8 +25,8 @@ from wled_controller.storage.automation_store import AutomationStore
 
 
 @pytest.fixture
-def mock_store(tmp_path) -> AutomationStore:
-    return AutomationStore(str(tmp_path / "auto.json"))
+def mock_store(tmp_db) -> AutomationStore:
+    return AutomationStore(tmp_db)
 
 
 @pytest.fixture