Stub out missing Elk endpoints

src/controllers/api/preferences.ts

@@ -0,0 +1,19 @@
+import { AppController } from '@/app.ts';
+
+/**
+ * Return a default set of preferences for compatibilty purposes.
+ * Clients like Soapbox do not use this.
+ *
+ * https://docs.joinmastodon.org/methods/preferences/
+ */
+const preferencesController: AppController = (c) => {
+  return c.json({
+    'posting:default:visibility': 'public',
+    'posting:default:sensitive': false,
+    'posting:default:language': null,
+    'reading:expand:media': 'default',
+    'reading:expand:spoilers': false,
+  });
+};
+
+export { preferencesController };