Lands docs/plans/2026-10-21_email-plan.md (merged plan, 399 lines) with Della's independent plan and her review of Ludwig's plan, from origin/della/email-planb0844a5ceonc3d88840c. Della's 10 BUILD-LOG and 4 SESSIONS lines are carried as appended. All rows are post-v1; no live mailbox, credential, DNS, spend, external mail or re-pin is authorized.