Merge pull request 'Use dedicated day, month and year controls for birthdays' (#70) from kyc-67 into main

docs/ux/kyc.md

@@ -211,3 +211,51 @@ smoke testing on the local demo opened the selector, searched for Poland and
 confirmed that the profile displays Poland after selection. Focused and full
 journey tests verify the stored `PL` code. Generated localization/build outputs
 remain ignored and uncommitted.
+
+## Birthday entry — task #67
+
+Task [#67](https://git.sendico.io/tech/sxchnge/issues/67), branch `kyc-67`.
+Delivery: [PR #70](https://git.sendico.io/tech/sxchnge/pulls/70).
+This change is stacked on the residence-country selector in PR #65; merge #65
+before the birthday PR.
+
+The profile uses labeled Day, Month and Year controls. Day and year accept numeric
+entry with birthday autofill hints; month selection uses localized month names
+and standard Material keyboard/touch interaction. Customers can enter their birth
+year directly. No calendar paging or transport-format punctuation is required.
+The controls share a row when space allows and stack at narrow widths or enlarged
+text sizes. English and Russian labels, month names and errors follow the app locale.
+
+Valid calendar dates are normalized to the existing `IdentityProfile.dateOfBirth`
+`YYYY-MM-DD` value through `IdentityProvider.updateProfile`. Partial, impossible
+and future dates clear that profile value so Continue cannot retain an earlier
+valid birthday. Local input components remain visible while correcting a date;
+complete invalid dates receive a specific live-region error below the group.
+Leap years, zero day/year and calendar rollover are checked. Today's date follows
+the existing model policy; no minimum age or arbitrary oldest birth year is added.
+Prefilled dates, locale changes and external profile replacement synchronize the
+controls. Back navigation restores the valid saved date. Busy state disables all
+three controls. Controllers are disposed with the widget.
+
+The existing DTO, mapper, service, domain model and provider boundaries are retained.
+No dependency, transport or backend change is needed. This remains part of the KYC
+preparation-to-submission journey defined above: existing acceptance, failure,
+retry and abandonment signals apply, without new field events or date collection.
+The existing server-side review measurement gaps remain unchanged.
+
+UX review and automated checks cover entry/correction, leap dates, invalid and
+future-date recovery, numeric restrictions, prefill/replacement/clearing, locale
+switching, disabled state, Tab/Enter/arrow-key month selection, Escape cancellation,
+and Russian controls/errors at 320px with 1.6 text scale. Labeled and minimum-size
+tap-target guidelines pass. Integration checks verify that invalid dates block
+Continue, Back preserves the birthday, and EN/RU flows still reach submission
+acceptance. Native screen-reader and mobile keyboard/autofill testing remain
+release checks; widget semantics are not a claim of device-level validation.
+
+Validation: all four changed Dart files pass the format check; `flutter analyze`
+in `frontend/app` reports no issues; `make test-frontend` passes all 230 tests,
+including the seven new birthday widget tests and the new navigation/gating test.
+`flutter build web` passes, including its Wasm compatibility dry run. Browser
+smoke testing of the release build entered 23 April 1990, verified the inline
+error for 31 April and restored 23 April without losing month or year.
+Generated localization and build outputs remain ignored and uncommitted.