feat: move ownership to member column instead of table column

migrations/2025-06-06-145916_guild_ownership_changes/up.sql

@@ -0,0 +1,14 @@
+-- Your SQL goes here
+ALTER TABLE guild_members
+ADD COLUMN is_owner BOOLEAN NOT NULL DEFAULT false;
+
+UPDATE guild_members gm
+SET is_owner = true
+FROM guilds g
+WHERE gm.guild_uuid = g.uuid AND gm.user_uuid = g.owner_uuid;
+
+CREATE UNIQUE INDEX one_owner_per_guild ON guild_members (guild_uuid)
+WHERE is_owner;
+
+ALTER TABLE guilds
+DROP COLUMN owner_uuid;