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_sync_clock_store.py

@@ -7,8 +7,8 @@ from wled_controller.storage.sync_clock_store import SyncClockStore
 
 
 @pytest.fixture
-def store(tmp_path) -> SyncClockStore:
-    return SyncClockStore(str(tmp_path / "sync_clocks.json"))
+def store(tmp_db) -> SyncClockStore:
+    return SyncClockStore(tmp_db)
 
 
 # ---------------------------------------------------------------------------
@@ -149,12 +149,14 @@ class TestSyncClockNameUniqueness:
 
 class TestSyncClockPersistence:
     def test_persist_and_reload(self, tmp_path):
-        path = str(tmp_path / "sc_persist.json")
-        s1 = SyncClockStore(path)
+        from wled_controller.storage.database import Database
+        db = Database(tmp_path / "sc_persist.db")
+        s1 = SyncClockStore(db)
         c = s1.create_clock(name="Persist", speed=2.5)
         cid = c.id
 
-        s2 = SyncClockStore(path)
+        s2 = SyncClockStore(db)
         loaded = s2.get_clock(cid)
         assert loaded.name == "Persist"
         assert loaded.speed == 2.5
+        db.close()