fix(servers): 主人可放弃服务器、管理员可删除服务器，由 reaper 归档世界后释放或移除

internal/store/migrations/0035_server_retire.sql

@@ -0,0 +1,8 @@
+-- An owner can give a server up, and an admin can retire one for good
+-- (PUT /servers/{name}/retirement). The request is recorded here and carried out
+-- by the reaper, the one component that deletes a world: on its next run it
+-- archives the world, deletes the volume and releases the server, and with
+-- retire_delete it also removes the MinecraftServer and marks this row deleted.
+-- Until then the server stays stopped and cannot be woken or claimed.
+ALTER TABLE servers ADD COLUMN retire_requested_at timestamptz;
+ALTER TABLE servers ADD COLUMN retire_delete boolean NOT NULL DEFAULT false;