MEMORY.md digest watchdog: surface rules added since 2026-07-13 in July 27 standup

Recurring biweekly MEMORY.md digest. At lease time: (1) inspect MEMORY.md additions/changes since 2026-07-13; (2) extract added rule headings/sections; (3) compose a 3-7 bullet digest; (4) write to memory/digests/2026-07-27-memory-additions.md and inject into the applicable standup body via metadata.body_inserts; (5) complete self and POST the next digest task for +14d. If Carson requests a different cadence, obey that.