Record BFF plan delivery in PR #35

docs/implementation.md

@@ -395,3 +395,8 @@ exit 0. Module/dependency inspection confirms standard-library-only dependencies
 Pinned source paths, source blobs and local documentation links were checked.
 Reviewed all new backend files and the task diff. No Flutter code changed;
 frontend tests and security scans were not run for this backend starter/plan task.
+
+Delivery: [PR #35](https://git.sendico.io/tech/sxchnge/pulls/35), `bff-34` into
+`main`, committed/pushed and unmerged. Issue #34 and PR metadata verified: backend
+label, tech owner, SXCHNGE project. Larger authentication/provider work remains
+separate from this completed audit and starter scope.