feat: add migration for workshop pause functionality

Author: janosbrodbeck

server/db/migrations/014_add_workshop_is_paused.sql

@@ -0,0 +1,5 @@
+-- Migration 014: Add is_paused to workshop
+-- Controls whether the workshop is paused (participants cannot play while paused).
+-- Default false: workshop is not paused.
+
+ALTER TABLE workshop ADD COLUMN is_paused boolean NOT NULL DEFAULT false;