Update UI and migrations, fix dockerfile

db/migrations/029_vk_poster_oauth_settings.sql

@@ -0,0 +1,5 @@
+INSERT INTO app_settings(key, value_json, value_type, title, description, category)
+VALUES
+  ('vk_poster_app_id', '""'::jsonb, 'str', 'VK OAuth app id', 'VK application id used for user OAuth code flow.', 'VK Poster'),
+  ('vk_poster_client_secret', '""'::jsonb, 'secret', 'VK OAuth client secret', 'Protected key from VK application settings. Used server-side to exchange code for user access token.', 'VK Poster')
+ON CONFLICT (key) DO NOTHING;