All four slices delivered (#753/#754/#757 + this PR); the durable architecture
decisions landed in ADR 126/225 and the retro lessons in adr-writing.mdc +
docs/Testing Guide.md. The transient project workspace (spec, plans, slice
plans) drops with the close-out. No external references to scrub.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Will Madden <madden@prisma.io>