bring in database

switch to just using source models (no extra db fields)
start re-implementing sync service

test/services/sync_service_test.dart

@@ -0,0 +1,79 @@
+import 'package:subtracks/database/database.dart';
+import 'package:subtracks/services/sync_services.dart';
+import 'package:subtracks/sources/subsonic/source.dart';
+import 'package:test/test.dart';
+
+import '../util/database.dart';
+import '../util/subsonic.dart';
+
+void main() {
+  late SubtracksDatabase db;
+  late SubsonicSource source;
+  late int sourceId;
+  late int sourceIdOther;
+
+  late SyncService sync;
+
+  setUp(() async {
+    db = testDatabase();
+    source = SubsonicSource(testServerClients()[Servers.navidrome]!);
+    sourceId = await db
+        .into(db.sources)
+        .insert(SourcesCompanion.insert(name: 'navidrome'));
+    sourceIdOther = await db
+        .into(db.sources)
+        .insert(SourcesCompanion.insert(name: 'other'));
+
+    sync = SyncService(
+      db: db,
+      source: source,
+      sourceId: sourceId,
+    );
+  });
+
+  tearDown(() async {
+    await db.close();
+  });
+
+  test('syncArtists', () async {
+    await db
+        .into(db.artists)
+        .insert(
+          ArtistsCompanion.insert(
+            sourceId: sourceId,
+            id: 'shouldBeDeleted',
+            name: 'shouldBeDeleted',
+          ),
+        );
+    await db
+        .into(db.artists)
+        .insert(
+          ArtistsCompanion.insert(
+            sourceId: sourceIdOther,
+            id: 'shouldBeKept',
+            name: 'shouldBeKept',
+          ),
+        );
+
+    await sync.syncArtists();
+
+    expect(
+      await db.managers.artists
+          .filter((f) => f.sourceId.equals(sourceId))
+          .count(),
+      equals(2),
+    );
+    expect(
+      await db.managers.artists
+          .filter((f) => f.id.equals('shouldBeDeleted'))
+          .getSingleOrNull(),
+      isNull,
+    );
+    expect(
+      await db.managers.artists
+          .filter((f) => f.id.equals('shouldBeKept'))
+          .getSingleOrNull(),
+      isNotNull,
+    );
+  });
+}