prisma db seed failed with "Cannot find module './seed.ts'" because
the spawned ts-node command inherited the user's cwd (apps/portal-bff/)
and resolved apps/portal-bff/prisma/seed.ts to
apps/portal-bff/apps/portal-bff/prisma/seed.ts (doubled).
pnpm run resets cwd to the package's root (workspace root) before
running the script. Routing prisma.seed through pnpm run db:seed
makes the path resolution cwd-invariant - works the same whether the
user invokes from the workspace root or from apps/portal-bff/.
Two-line diff: new db:seed script + prisma.seed delegates to it.
Side benefit: pnpm db:seed is directly callable.