Record onboarding UX and analytics delivery

docs/implementation.md

@@ -117,3 +117,8 @@ sink and a journey recorder; auth service decorators keep collection independent
 of widgets. A PostHog adapter can replace the sink later; no actual SDK or data
 transmission is included. The [journey contract](ux/auth-journeys.md) records event
 semantics, metrics, privacy constraints, windows, validation and limitations.
+
+Delivery: [PR #13](https://git.sendico.io/tech/sxchnge/pulls/13), `onboarding-12`.
+Implementation commit `f1cbf64`; 68 tests and affected-package analysis/formatting
+plus web build passed. Final browser verification confirms accessible recipient
+text and keyboard recovery. No merge or actual PostHog collection was performed.