add: chat notifications

use sql_chanes/notifications_tag.sql; ignore first statement if you never used a preview commit

sql_changes/notifications_tag.sql

@@ -0,0 +1,7 @@
+-- remove users subscriptions
+ALTER TABLE users
+DROP COLUMN subscriptions;
+
+-- add notifications tag
+ALTER TABLE notifications
+ADD COLUMN tag TEXT NOT NULL DEFAULT '';

sql_changes/users_subscriptions.sql

@@ -1,2 +0,0 @@
-ALTER TABLE users
-ADD COLUMN subscriptions TEXT NOT NULL DEFAULT '{}';