Record UX simplicity guidance delivery

docs/implementation.md

@@ -141,3 +141,14 @@ current packages, app/website commands, verification previews, analytics limits,
 skill location and contribution workflow. Local links and diff checks pass;
 commands and prerequisites were checked against repository configuration.
 Documentation only; no runtime tests were run.
+
+## UX simplicity preference
+
+Task [#26](https://git.sendico.io/tech/sxchnge/issues/26), delivered in
+[PR #27](https://git.sendico.io/tech/sxchnge/pulls/27) on `skills-26`, makes
+simplicity an explicit preference in the UX Design skill and its review checklist.
+Prefer fewer concepts, choices, and controls when they serve the same need; retain
+essential information, accessibility, and recovery. Documentation only.
+Validation: skill-creator `quick_validate.py` passed in an isolated environment
+with PyYAML (the system Python lacked it); `git diff --check` passed. No runtime
+tests were needed. The PR is not merged.