feat: add comment field to ChecklistResult for error descriptions

server/prisma/migrations/20260524115044_add_checklist_comment/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "ChecklistResult" ADD COLUMN "comment" TEXT;

server/prisma/schema.prisma

@@ -346,6 +346,7 @@ model ChecklistResult {
   id        String   @id @default(cuid())
   itemKey   String   @unique
   passed    Boolean
+  comment   String?
   checkedAt DateTime @default(now())
   updatedAt DateTime @updatedAt
 }