Set up default currency accounts automatically (#72)

frontend/app/lib/workspace/transfer.dart

@@ -256,11 +256,23 @@ class TransferPageState extends State<TransferPage> {
                         ),
                       ] else ...[
                         if (accounts.isEmpty) ...[
-                          Text(wallet.loading ? l.wWorking : l.wEmptyAccounts),
-                          TextButton(
-                            onPressed: wallet.loading ? null : wallet.refresh,
-                            child: Text(l.wRefresh),
+                          Semantics(
+                            liveRegion: true,
+                            child: Text(
+                              wallet.loading ||
+                                      (!wallet.failed && wallet.data == null)
+                                  ? l.wAccountsLoading
+                                  : wallet.failed
+                                  ? l.wAccountsFailed
+                                  : l.wEmptyAccounts,
+                            ),
                           ),
+                          if (!wallet.loading &&
+                              (wallet.failed || wallet.data != null))
+                            TextButton(
+                              onPressed: wallet.refresh,
+                              child: Text(l.wAccountsRetry),
+                            ),
                         ] else ...[
                           DropdownButtonFormField<String>(
                             key: ValueKey('source-${p.source}'),