Set up default currency accounts automatically (#72)

frontend/app/lib/workspace/accounts.dart

@@ -65,15 +65,34 @@ class AccountsPage extends StatelessWidget {
               ),
               const SizedBox(height: 28),
               if (p.loading) const LinearProgressIndicator(),
-              if (p.failed)
+              if ((p.loading || (!p.failed && p.data == null)) &&
+                  accounts.isEmpty)
+                Semantics(liveRegion: true, child: Text(l.wAccountsLoading)),
+              if (p.failed && accounts.isNotEmpty)
                 Padding(
                   padding: const EdgeInsets.symmetric(vertical: 16),
                   child: Text(l.wUnavailable, style: TextStyle(color: c.error)),
                 ),
-              if (!p.loading && accounts.isEmpty) Text(l.wEmptyAccounts),
+              if (!p.loading &&
+                  accounts.isEmpty &&
+                  (p.failed || p.data != null)) ...[
+                Semantics(
+                  liveRegion: true,
+                  child: Text(p.failed ? l.wAccountsFailed : l.wEmptyAccounts),
+                ),
+                Align(
+                  alignment: Alignment.centerLeft,
+                  child: TextButton(
+                    onPressed: p.refresh,
+                    child: Text(l.wAccountsRetry),
+                  ),
+                ),
+              ],
               if (accountId != null &&
                   p.account(accountId) == null &&
-                  !p.loading)
+                  !p.loading &&
+                  !p.failed &&
+                  p.data != null)
                 Text(l.wNotFound),
               if (selected != null) ...[
                 const SizedBox(height: 24),

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}'),