update README.md and enhance postgres setup and prisma migrations

[sJJdGG]

Updated README with the missing Postgres CREATEDB grant and a note about using --name for non‑interactive shells.

Changes in README.md:

• Added ALTER ROLE fate CREATEDB; in the Postgres setup block.
• Added note about pnpm prisma migrate dev --name init to avoid interactive prompt (less hiccup for agents).

Why:

Prisma’s “shadow database” is a temporary database used during prisma migrate dev to safely compute and validate migrations. Prisma applies the migration history to the shadow DB, compares it with the current schema, and uses that diff to generate new migrations or detect drift—without touching your real development database. It creates and drops this shadow DB automatically, which is why the DB user needs CREATEDB privileges.