Select residence country by searchable name (#64)

docs/ux/kyc.md

@@ -167,3 +167,46 @@ This is a display correction within the existing KYC journey, so no additional
 analytics events or financial data collection are introduced. Tests cover mapping
 without inferring remaining, unused/exhausted/over-cap/zero-cap ratios and EN/RU
 usage display at 320px with 1.6 text scaling.
+
+## Residence country selection — task #64
+
+Task [#64](https://git.sendico.io/tech/sxchnge/issues/64), branch `kyc-64`.
+The profile now shows a country name and opens a searchable country list instead
+of asking customers to type a two-letter code. Names follow the English/Russian
+app locale. Search accepts localized or English names and two-letter codes,
+ignoring case and surrounding whitespace. Selection updates only
+`IdentityProfile.residenceCountry` with the country code; the existing provider,
+service, mapper and transport contracts remain unchanged.
+
+The `country_picker` dependency supplies bundled country data, code lookup and
+translations through `CountryService` and `CountryLocalizations`. Flutter Material
+controls provide the search interface, explicit no-results recovery, minimum
+touch targets, keyboard selection, a selected-state checkmark, Back and Escape.
+The package's built-in list omits explicit no-results feedback and uses shorter
+row targets, so its data/localizations are reused with standard Material controls.
+There is no remote lookup, copied country table or extra application provider.
+Cancelling preserves the current profile, prefilled codes display names, busy
+state disables opening the selector, and the search controller is disposed with
+its dialog. The list is a data catalogue; backend eligibility remains authoritative.
+
+This change stays within the existing KYC preparation/submission journey and its
+measurement definitions above. No selector events, queries, names or country
+codes are added to telemetry. Existing acceptance/failure/retry/abandonment
+signals and documented server-side review measurement gaps still apply.
+
+Focused widget checks cover name/code search, code-only updates, reselection,
+cancel, no-results recovery, clearing search, saved values, locale changes,
+Russian names, disabled state, keyboard activation/selection/Escape and labeled
+touch targets. A long country name fits at 320px with 1.6 text scale. Existing
+EN/RU verification journeys now select a country and assert the profile code
+before continuing through document submission. Native screen-reader and device
+keyboard testing remain release checks; widget semantics checks do not establish
+those device outcomes.
+
+Validation: five changed Dart files passed the format check; `flutter analyze`
+in `frontend/app` reported no issues; `make test-frontend` passed all 222 tests;
+and `flutter build web` passed, including its Wasm compatibility dry run. Browser
+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.