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/storage/test_value_source_store.py

@@ -14,8 +14,8 @@ from wled_controller.storage.value_source_store import ValueSourceStore
 
 
 @pytest.fixture
-def store(tmp_path) -> ValueSourceStore:
-    return ValueSourceStore(str(tmp_path / "value_sources.json"))
+def store(tmp_db) -> ValueSourceStore:
+    return ValueSourceStore(tmp_db)
 
 
 # ---------------------------------------------------------------------------
@@ -247,13 +247,15 @@ class TestValueSourceNameUniqueness:
 
 class TestValueSourcePersistence:
     def test_persist_and_reload(self, tmp_path):
-        path = str(tmp_path / "vs_persist.json")
-        s1 = ValueSourceStore(path)
+        from wled_controller.storage.database import Database
+        db = Database(tmp_path / "vs_persist.db")
+        s1 = ValueSourceStore(db)
         src = s1.create_source("Persist", "static", value=0.42)
         sid = src.id
 
-        s2 = ValueSourceStore(path)
+        s2 = ValueSourceStore(db)
         loaded = s2.get_source(sid)
         assert loaded.name == "Persist"
         assert isinstance(loaded, StaticValueSource)
         assert loaded.value == 0.42
+        db.close()