Initial commit: YouTube Studio Flow (backend, frontend, infrastructure, docs)

backend/prisma/migrations/20260608000002_fix_supplemental_video_ids_default/migration.sql

@@ -0,0 +1,2 @@
+-- Fix: remove the default from supplementalVideoIds — column was added without a default in DB
+ALTER TABLE "Channel" ALTER COLUMN "supplementalVideoIds" DROP DEFAULT;