Refactor widgets & imports; add krow_domain

Add local krow_domain dependency to client, staff apps and client home package. Numerous UI/widget cleanups across features: add const where applicable, use explicit List<Widget> types and List<Widget>.generate, add super.key to constructors, tighten BlocProvider generics, replace some Containers with SizedBox, and simplify InputDecoration/Border constructors. Fix API error handler to return a const UnknownException. Update internal imports to package-style paths (staff_home, staff_payments, staff_main repository interface) and normalize Flutter imports (use material.dart). Add missing braces for early returns in tax form pages. Mostly formatting and small API/typing refactors with no behavioral changes intended.

apps/mobile/packages/features/client/client_coverage/lib/src/presentation/widgets/coverage_page_skeleton/shift_card_skeleton.dart

@@ -14,20 +14,20 @@ class ShiftCardSkeleton extends StatelessWidget {
         borderRadius: UiConstants.radiusLg,
       ),
       clipBehavior: Clip.antiAlias,
-      child: Column(
-        children: [
+        child: Column(
+          children: <Widget>[
           // Shift header
           Padding(
             padding: const EdgeInsets.all(UiConstants.space4),
             child: Column(
               crossAxisAlignment: CrossAxisAlignment.start,
-              children: [
+              children: <Widget>[
                 const UiShimmerLine(width: 180, height: 16),
                 const SizedBox(height: UiConstants.space2),
                 const UiShimmerLine(width: 120, height: 12),
                 const SizedBox(height: UiConstants.space2),
                 Row(
-                  children: [
+                  children: <Widget>[
                     const UiShimmerLine(width: 80, height: 12),
                     const Spacer(),
                     UiShimmerBox(
@@ -47,7 +47,7 @@ class ShiftCardSkeleton extends StatelessWidget {
               horizontal: UiConstants.space3,
             ).copyWith(bottom: UiConstants.space3),
             child: const Column(
-              children: [
+              children: <Widget>[
                 UiShimmerListItem(),
                 UiShimmerListItem(),
               ],