Blog refresh: Improving Query Performance with Indexes part 3, Hash Indexes (#8040)

Completes the series refresh (#8029 part 2, #8039 part 1). Rebuilt for
Prisma ORM 7.8: prisma-client generator, driver adapter, local Prisma
Postgres via prisma dev, measurements re-run end-to-end today (seq scan
64.1ms -> hash index 1.567ms over 500k rows, ~41x, PostgreSQL 17).
content-seo-geo pass: answer-first lead, Updated callout, FAQ accordions,
no inline TOC, canonical links only. Reviewed by Martin.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: Nurul Sundarani <sundarani@prisma.io>

Author: 3 people