31b6724a52
Follows the base PR's renumber (0081 was already taken; main is on 0082). Update every `PRD 0081` reference in the gateway-attach code, tests, and ADR 0006, plus ADR 0006's link to the PRD file. No behaviour change. Refs #516, #519. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>